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Abstract Writing: A Step-by-Step Guide With Tips & Examples

Table of Contents

Introduction

Abstracts of research papers have always played an essential role in describing your research concisely and clearly to researchers and editors of journals, enticing them to continue reading. However, with the widespread availability of scientific databases, the need to write a convincing abstract is more crucial now than during the time of paper-bound manuscripts.

Abstracts serve to "sell" your research and can be compared with your "executive outline" of a resume or, rather, a formal summary of the critical aspects of your work. Also, it can be the "gist" of your study. Since most educational research is done online, it's a sign that you have a shorter time for impressing your readers, and have more competition from other abstracts that are available to be read.

The APCI (Academic Publishing and Conferences International) articulates 12 issues or points considered during the final approval process for conferences & journals and emphasises the importance of writing an abstract that checks all these boxes (12 points). Since it's the only opportunity you have to captivate your readers, you must invest time and effort in creating an abstract that accurately reflects the critical points of your research.

With that in mind, let’s head over to understand and discover the core concept and guidelines to create a substantial abstract. Also, learn how to organise the ideas or plots into an effective abstract that will be awe-inspiring to the readers you want to reach.

What is Abstract? Definition and Overview

The word "Abstract' is derived from Latin abstractus meaning "drawn off." This etymological meaning also applies to art movements as well as music, like abstract expressionism. In this context, it refers to the revealing of the artist's intention.

Based on this, you can determine the meaning of an abstract: A condensed research summary. It must be self-contained and independent of the body of the research. However, it should outline the subject, the strategies used to study the problem, and the methods implemented to attain the outcomes. The specific elements of the study differ based on the area of study; however, together, it must be a succinct summary of the entire research paper.

Abstracts are typically written at the end of the paper, even though it serves as a prologue. In general, the abstract must be in a position to:

• Describe the paper.
• Identify the problem or the issue at hand.
• Explain to the reader the research process, the results you came up with, and what conclusion you've reached using these results.
• Include keywords to guide your strategy and the content.

Furthermore, the abstract you submit should not reflect upon any of  the following elements:

• Examine, analyse or defend the paper or your opinion.
• What you want to study, achieve or discover.
• Be redundant or irrelevant.

After reading an abstract, your audience should understand the reason - what the research was about in the first place, what the study has revealed and how it can be utilised or can be used to benefit others. You can understand the importance of abstract by knowing the fact that the abstract is the most frequently read portion of any research paper. In simpler terms, it should contain all the main points of the research paper.

What is the Purpose of an Abstract?

Abstracts are typically an essential requirement for research papers; however, it's not an obligation to preserve traditional reasons without any purpose. Abstracts allow readers to scan the text to determine whether it is relevant to their research or studies. The abstract allows other researchers to decide if your research paper can provide them with some additional information. A good abstract paves the interest of the audience to pore through your entire paper to find the content or context they're searching for.

Abstract writing is essential for indexing, as well. The Digital Repository of academic papers makes use of abstracts to index the entire content of academic research papers. Like meta descriptions in the regular Google outcomes, abstracts must include keywords that help researchers locate what they seek.

Types of Abstract

Informative and Descriptive are two kinds of abstracts often used in scientific writing.

A descriptive abstract gives readers an outline of the author's main points in their study. The reader can determine if they want to stick to the research work, based on their interest in the topic. An abstract that is descriptive is similar to the contents table of books, however, the format of an abstract depicts complete sentences encapsulated in one paragraph. It is unfortunate that the abstract can't be used as a substitute for reading a piece of writing because it's just an overview, which omits readers from getting an entire view. Also, it cannot be a way to fill in the gaps the reader may have after reading this kind of abstract since it does not contain crucial information needed to evaluate the article.

To conclude, a descriptive abstract is:

• A simple summary of the task, just summarises the work, but some researchers think it is much more of an outline
• Typically, the length is approximately 100 words. It is too short when compared to an informative abstract.
• A brief explanation but doesn't provide the reader with the complete information they need;
• An overview that omits conclusions and results

An informative abstract is a comprehensive outline of the research. There are times when people rely on the abstract as an information source. And the reason is why it is crucial to provide entire data of particular research. A well-written, informative abstract could be a good substitute for the remainder of the paper on its own.

A well-written abstract typically follows a particular style. The author begins by providing the identifying information, backed by citations and other identifiers of the papers. Then, the major elements are summarised to make the reader aware of the study. It is followed by the methodology and all-important findings from the study. The conclusion then presents study results and ends the abstract with a comprehensive summary.

In a nutshell, an informative abstract:

• Has a length that can vary, based on the subject, but is not longer than 300 words.
• Contains all the content-like methods and intentions
• Offers evidence and possible recommendations.

Informative Abstracts are more frequent than descriptive abstracts because of their extensive content and linkage to the topic specifically. You should select different types of abstracts to papers based on their length: informative abstracts for extended and more complex abstracts and descriptive ones for simpler and shorter research papers.

What are the Characteristics of a Good Abstract?

• A good abstract clearly defines the goals and purposes of the study.
• It should clearly describe the research methodology with a primary focus on data gathering, processing, and subsequent analysis.
• A good abstract should provide specific research findings.
• It presents the principal conclusions of the systematic study.
• It should be concise, clear, and relevant to the field of study.
• A well-designed abstract should be unifying and coherent.
• It is easy to grasp and free of technical jargon.
• It is written impartially and objectively.

What are the various sections of an ideal Abstract?

By now, you must have gained some concrete idea of the essential elements that your abstract needs to convey . Accordingly, the information is broken down into six key sections of the abstract, which include:

An Introduction or Background

Research methodology, objectives and goals, limitations.

Let's go over them in detail.

The introduction, also known as background, is the most concise part of your abstract. Ideally, it comprises a couple of sentences. Some researchers only write one sentence to introduce their abstract. The idea behind this is to guide readers through the key factors that led to your study.

It's understandable that this information might seem difficult to explain in a couple of sentences. For example, think about the following two questions like the background of your study:

• What is currently available about the subject with respect to the paper being discussed?
• What isn't understood about this issue? (This is the subject of your research)

While writing the abstract’s introduction, make sure that it is not lengthy. Because if it crosses the word limit, it may eat up the words meant to be used for providing other key information.

Research methodology is where you describe the theories and techniques you used in your research. It is recommended that you describe what you have done and the method you used to get your thorough investigation results. Certainly, it is the second-longest paragraph in the abstract.

In the research methodology section, it is essential to mention the kind of research you conducted; for instance, qualitative research or quantitative research (this will guide your research methodology too) . If you've conducted quantitative research, your abstract should contain information like the sample size, data collection method, sampling techniques, and duration of the study. Likewise, your abstract should reflect observational data, opinions, questionnaires (especially the non-numerical data) if you work on qualitative research.

The research objectives and goals speak about what you intend to accomplish with your research. The majority of research projects focus on the long-term effects of a project, and the goals focus on the immediate, short-term outcomes of the research. It is possible to summarise both in just multiple sentences.

In stating your objectives and goals, you give readers a picture of the scope of the study, its depth and the direction your research ultimately follows. Your readers can evaluate the results of your research against the goals and stated objectives to determine if you have achieved the goal of your research.

In the end, your readers are more attracted by the results you've obtained through your study. Therefore, you must take the time to explain each relevant result and explain how they impact your research. The results section exists as the longest in your abstract, and nothing should diminish its reach or quality.

One of the most important things you should adhere to is to spell out details and figures on the results of your research.

Instead of making a vague assertion such as, "We noticed that response rates varied greatly between respondents with high incomes and those with low incomes", Try these: "The response rate was higher for high-income respondents than those with lower incomes (59 30 percent vs. 30 percent in both cases; P<0.01)."

You're likely to encounter certain obstacles during your research. It could have been during data collection or even during conducting the sample . Whatever the issue, it's essential to inform your readers about them and their effects on the research.

Research limitations offer an opportunity to suggest further and deep research. If, for instance, you were forced to change for convenient sampling and snowball samples because of difficulties in reaching well-suited research participants, then you should mention this reason when you write your research abstract. In addition, a lack of prior studies on the subject could hinder your research.

Your conclusion should include the same number of sentences to wrap the abstract as the introduction. The majority of researchers offer an idea of the consequences of their research in this case.

Your conclusion should include three essential components:

• A significant take-home message.
• Corresponding important findings.
• The Interpretation.

Even though the conclusion of your abstract needs to be brief, it can have an enormous influence on the way that readers view your research. Therefore, make use of this section to reinforce the central message from your research. Be sure that your statements reflect the actual results and the methods you used to conduct your research.

Good Abstract Examples

Abstract example #1.

Children’s consumption behavior in response to food product placements in movies.

The abstract:

"Almost all research into the effects of brand placements on children has focused on the brand's attitudes or behavior intentions. Based on the significant differences between attitudes and behavioral intentions on one hand and actual behavior on the other hand, this study examines the impact of placements by brands on children's eating habits. Children aged 6-14 years old were shown an excerpt from the popular film Alvin and the Chipmunks and were shown places for the item Cheese Balls. Three different versions were developed with no placements, one with moderately frequent placements and the third with the highest frequency of placement. The results revealed that exposure to high-frequency places had a profound effect on snack consumption, however, there was no impact on consumer attitudes towards brands or products. The effects were not dependent on the age of the children. These findings are of major importance to researchers studying consumer behavior as well as nutrition experts as well as policy regulators."

Abstract Example #2

Social comparisons on social media: The impact of Facebook on young women’s body image concerns and mood. The abstract:

"The research conducted in this study investigated the effects of Facebook use on women's moods and body image if the effects are different from an internet-based fashion journal and if the appearance comparison tendencies moderate one or more of these effects. Participants who were female ( N = 112) were randomly allocated to spend 10 minutes exploring their Facebook account or a magazine's website or an appearance neutral control website prior to completing state assessments of body dissatisfaction, mood, and differences in appearance (weight-related and facial hair, face, and skin). Participants also completed a test of the tendency to compare appearances. The participants who used Facebook were reported to be more depressed than those who stayed on the control site. In addition, women who have the tendency to compare appearances reported more facial, hair and skin-related issues following Facebook exposure than when they were exposed to the control site. Due to its popularity it is imperative to conduct more research to understand the effect that Facebook affects the way people view themselves."

Abstract Example #3

The Relationship Between Cell Phone Use and Academic Performance in a Sample of U.S. College Students

"The cellphone is always present on campuses of colleges and is often utilised in situations in which learning takes place. The study examined the connection between the use of cell phones and the actual grades point average (GPA) after adjusting for predictors that are known to be a factor. In the end 536 students in the undergraduate program from 82 self-reported majors of an enormous, public institution were studied. Hierarchical analysis ( R 2 = .449) showed that use of mobile phones is significantly ( p < .001) and negative (b equal to -.164) connected to the actual college GPA, after taking into account factors such as demographics, self-efficacy in self-regulated learning, self-efficacy to improve academic performance, and the actual high school GPA that were all important predictors ( p < .05). Therefore, after adjusting for other known predictors increasing cell phone usage was associated with lower academic performance. While more research is required to determine the mechanisms behind these results, they suggest the need to educate teachers and students to the possible academic risks that are associated with high-frequency mobile phone usage."

Quick tips on writing a good abstract

There exists a common dilemma among early age researchers whether to write the abstract at first or last? However, it's recommended to compose your abstract when you've completed the research since you'll have all the information to give to your readers. You can, however, write a draft at the beginning of your research and add in any gaps later.

If you find abstract writing a herculean task, here are the few tips to help you with it:

1. Always develop a framework to support your abstract

Before writing, ensure you create a clear outline for your abstract. Divide it into sections and draw the primary and supporting elements in each one. You can include keywords and a few sentences that convey the essence of your message.

2. Review Other Abstracts

Abstracts are among the most frequently used research documents, and thousands of them were written in the past. Therefore, prior to writing yours, take a look at some examples from other abstracts. There are plenty of examples of abstracts for dissertations in the dissertation and thesis databases.

3. Avoid Jargon To the Maximum

When you write your abstract, focus on simplicity over formality. You should  write in simple language, and avoid excessive filler words or ambiguous sentences. Keep in mind that your abstract must be readable to those who aren't acquainted with your subject.

4. Focus on Your Research

It's a given fact that the abstract you write should be about your research and the findings you've made. It is not the right time to mention secondary and primary data sources unless it's absolutely required.

Conclusion: How to Structure an Interesting Abstract?

Abstracts are a short outline of your essay. However, it's among the most important, if not the most important. The process of writing an abstract is not straightforward. A few early-age researchers tend to begin by writing it, thinking they are doing it to "tease" the next step (the document itself). However, it is better to treat it as a spoiler.

The simple, concise style of the abstract lends itself to a well-written and well-investigated study. If your research paper doesn't provide definitive results, or the goal of your research is questioned, so will the abstract. Thus, only write your abstract after witnessing your findings and put your findings in the context of a larger scenario.

The process of writing an abstract can be daunting, but with these guidelines, you will succeed. The most efficient method of writing an excellent abstract is to centre the primary points of your abstract, including the research question and goals methods, as well as key results.

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Writing an Abstract for Your Research Paper

Definition and Purpose of Abstracts

An abstract is a short summary of your (published or unpublished) research paper, usually about a paragraph (c. 6-7 sentences, 150-250 words) long. A well-written abstract serves multiple purposes:

• an abstract lets readers get the gist or essence of your paper or article quickly, in order to decide whether to read the full paper;
• an abstract prepares readers to follow the detailed information, analyses, and arguments in your full paper;
• and, later, an abstract helps readers remember key points from your paper.

It’s also worth remembering that search engines and bibliographic databases use abstracts, as well as the title, to identify key terms for indexing your published paper. So what you include in your abstract and in your title are crucial for helping other researchers find your paper or article.

If you are writing an abstract for a course paper, your professor may give you specific guidelines for what to include and how to organize your abstract. Similarly, academic journals often have specific requirements for abstracts. So in addition to following the advice on this page, you should be sure to look for and follow any guidelines from the course or journal you’re writing for.

The Contents of an Abstract

Abstracts contain most of the following kinds of information in brief form. The body of your paper will, of course, develop and explain these ideas much more fully. As you will see in the samples below, the proportion of your abstract that you devote to each kind of information—and the sequence of that information—will vary, depending on the nature and genre of the paper that you are summarizing in your abstract. And in some cases, some of this information is implied, rather than stated explicitly. The Publication Manual of the American Psychological Association , which is widely used in the social sciences, gives specific guidelines for what to include in the abstract for different kinds of papers—for empirical studies, literature reviews or meta-analyses, theoretical papers, methodological papers, and case studies.

Here are the typical kinds of information found in most abstracts:

• the context or background information for your research; the general topic under study; the specific topic of your research
• the central questions or statement of the problem your research addresses
• what’s already known about this question, what previous research has done or shown
• the main reason(s) , the exigency, the rationale , the goals for your research—Why is it important to address these questions? Are you, for example, examining a new topic? Why is that topic worth examining? Are you filling a gap in previous research? Applying new methods to take a fresh look at existing ideas or data? Resolving a dispute within the literature in your field? . . .
• your research and/or analytical methods
• your main findings , results , or arguments
• the significance or implications of your findings or arguments.

Your abstract should be intelligible on its own, without a reader’s having to read your entire paper. And in an abstract, you usually do not cite references—most of your abstract will describe what you have studied in your research and what you have found and what you argue in your paper. In the body of your paper, you will cite the specific literature that informs your research.

When to Write Your Abstract

Although you might be tempted to write your abstract first because it will appear as the very first part of your paper, it’s a good idea to wait to write your abstract until after you’ve drafted your full paper, so that you know what you’re summarizing.

What follows are some sample abstracts in published papers or articles, all written by faculty at UW-Madison who come from a variety of disciplines. We have annotated these samples to help you see the work that these authors are doing within their abstracts.

Choosing Verb Tenses within Your Abstract

The social science sample (Sample 1) below uses the present tense to describe general facts and interpretations that have been and are currently true, including the prevailing explanation for the social phenomenon under study. That abstract also uses the present tense to describe the methods, the findings, the arguments, and the implications of the findings from their new research study. The authors use the past tense to describe previous research.

The humanities sample (Sample 2) below uses the past tense to describe completed events in the past (the texts created in the pulp fiction industry in the 1970s and 80s) and uses the present tense to describe what is happening in those texts, to explain the significance or meaning of those texts, and to describe the arguments presented in the article.

The science samples (Samples 3 and 4) below use the past tense to describe what previous research studies have done and the research the authors have conducted, the methods they have followed, and what they have found. In their rationale or justification for their research (what remains to be done), they use the present tense. They also use the present tense to introduce their study (in Sample 3, “Here we report . . .”) and to explain the significance of their study (In Sample 3, This reprogramming . . . “provides a scalable cell source for. . .”).

Sample Abstract 1

From the social sciences.

Reporting new findings about the reasons for increasing economic homogamy among spouses

Gonalons-Pons, Pilar, and Christine R. Schwartz. “Trends in Economic Homogamy: Changes in Assortative Mating or the Division of Labor in Marriage?” Demography , vol. 54, no. 3, 2017, pp. 985-1005.

Sample Abstract 2

From the humanities.

Analyzing underground pulp fiction publications in Tanzania, this article makes an argument about the cultural significance of those publications

Emily Callaci. “Street Textuality: Socialism, Masculinity, and Urban Belonging in Tanzania’s Pulp Fiction Publishing Industry, 1975-1985.” Comparative Studies in Society and History , vol. 59, no. 1, 2017, pp. 183-210.

Sample Abstract/Summary 3

From the sciences.

Reporting a new method for reprogramming adult mouse fibroblasts into induced cardiac progenitor cells

Lalit, Pratik A., Max R. Salick, Daryl O. Nelson, Jayne M. Squirrell, Christina M. Shafer, Neel G. Patel, Imaan Saeed, Eric G. Schmuck, Yogananda S. Markandeya, Rachel Wong, Martin R. Lea, Kevin W. Eliceiri, Timothy A. Hacker, Wendy C. Crone, Michael Kyba, Daniel J. Garry, Ron Stewart, James A. Thomson, Karen M. Downs, Gary E. Lyons, and Timothy J. Kamp. “Lineage Reprogramming of Fibroblasts into Proliferative Induced Cardiac Progenitor Cells by Defined Factors.” Cell Stem Cell , vol. 18, 2016, pp. 354-367.

Sample Abstract 4, a Structured Abstract

Reporting results about the effectiveness of antibiotic therapy in managing acute bacterial sinusitis, from a rigorously controlled study

Note: This journal requires authors to organize their abstract into four specific sections, with strict word limits. Because the headings for this structured abstract are self-explanatory, we have chosen not to add annotations to this sample abstract.

Wald, Ellen R., David Nash, and Jens Eickhoff. “Effectiveness of Amoxicillin/Clavulanate Potassium in the Treatment of Acute Bacterial Sinusitis in Children.” Pediatrics , vol. 124, no. 1, 2009, pp. 9-15.

“OBJECTIVE: The role of antibiotic therapy in managing acute bacterial sinusitis (ABS) in children is controversial. The purpose of this study was to determine the effectiveness of high-dose amoxicillin/potassium clavulanate in the treatment of children diagnosed with ABS.

METHODS : This was a randomized, double-blind, placebo-controlled study. Children 1 to 10 years of age with a clinical presentation compatible with ABS were eligible for participation. Patients were stratified according to age (<6 or ≥6 years) and clinical severity and randomly assigned to receive either amoxicillin (90 mg/kg) with potassium clavulanate (6.4 mg/kg) or placebo. A symptom survey was performed on days 0, 1, 2, 3, 5, 7, 10, 20, and 30. Patients were examined on day 14. Children’s conditions were rated as cured, improved, or failed according to scoring rules.

RESULTS: Two thousand one hundred thirty-five children with respiratory complaints were screened for enrollment; 139 (6.5%) had ABS. Fifty-eight patients were enrolled, and 56 were randomly assigned. The mean age was 6630 months. Fifty (89%) patients presented with persistent symptoms, and 6 (11%) presented with nonpersistent symptoms. In 24 (43%) children, the illness was classified as mild, whereas in the remaining 32 (57%) children it was severe. Of the 28 children who received the antibiotic, 14 (50%) were cured, 4 (14%) were improved, 4(14%) experienced treatment failure, and 6 (21%) withdrew. Of the 28children who received placebo, 4 (14%) were cured, 5 (18%) improved, and 19 (68%) experienced treatment failure. Children receiving the antibiotic were more likely to be cured (50% vs 14%) and less likely to have treatment failure (14% vs 68%) than children receiving the placebo.

CONCLUSIONS : ABS is a common complication of viral upper respiratory infections. Amoxicillin/potassium clavulanate results in significantly more cures and fewer failures than placebo, according to parental report of time to resolution.” (9)

Some Excellent Advice about Writing Abstracts for Basic Science Research Papers, by Professor Adriano Aguzzi from the Institute of Neuropathology at the University of Zurich:

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How to Write an Abstract (With Examples)

Sarah Oakley

Table of Contents

What is an abstract in a paper, how long should an abstract be, 5 steps for writing an abstract, examples of an abstract, how prowritingaid can help you write an abstract.

If you are writing a scientific research paper or a book proposal, you need to know how to write an abstract, which summarizes the contents of the paper or book.

When researchers are looking for peer-reviewed papers to use in their studies, the first place they will check is the abstract to see if it applies to their work. Therefore, your abstract is one of the most important parts of your entire paper.

In this article, we’ll explain what an abstract is, what it should include, and how to write one.

An abstract is a concise summary of the details within a report. Some abstracts give more details than others, but the main things you’ll be talking about are why you conducted the research, what you did, and what the results show.

When a reader is deciding whether to read your paper completely, they will first look at the abstract. You need to be concise in your abstract and give the reader the most important information so they can determine if they want to read the whole paper.

Remember that an abstract is the last thing you’ll want to write for the research paper because it directly references parts of the report. If you haven’t written the report, you won’t know what to include in your abstract.

If you are writing a paper for a journal or an assignment, the publication or academic institution might have specific formatting rules for how long your abstract should be. However, if they don’t, most abstracts are between 150 and 300 words long.

A short word count means your writing has to be precise and without filler words or phrases. Once you’ve written a first draft, you can always use an editing tool, such as ProWritingAid, to identify areas where you can reduce words and increase readability.

If your abstract is over the word limit, and you’ve edited it but still can’t figure out how to reduce it further, your abstract might include some things that aren’t needed. Here’s a list of three elements you can remove from your abstract:

Discussion : You don’t need to go into detail about the findings of your research because your reader will find your discussion within the paper.

Definition of terms : Your readers are interested the field you are writing about, so they are likely to understand the terms you are using. If not, they can always look them up. Your readers do not expect you to give a definition of terms in your abstract.

References and citations : You can mention there have been studies that support or have inspired your research, but you do not need to give details as the reader will find them in your bibliography.

Good writing = better grades

ProWritingAid will help you improve the style, strength, and clarity of all your assignments.

If you’ve never written an abstract before, and you’re wondering how to write an abstract, we’ve got some steps for you to follow. It’s best to start with planning your abstract, so we’ve outlined the details you need to include in your plan before you write.

Remember to consider your audience when you’re planning and writing your abstract. They are likely to skim read your abstract, so you want to be sure your abstract delivers all the information they’re expecting to see at key points.

1. What Should an Abstract Include?

Abstracts have a lot of information to cover in a short number of words, so it’s important to know what to include. There are three elements that need to be present in your abstract:

Your context is the background for where your research sits within your field of study. You should briefly mention any previous scientific papers or experiments that have led to your hypothesis and how research develops in those studies.

Your hypothesis is your prediction of what your study will show. As you are writing your abstract after you have conducted your research, you should still include your hypothesis in your abstract because it shows the motivation for your paper.

Throughout your abstract, you also need to include keywords and phrases that will help researchers to find your article in the databases they’re searching. Make sure the keywords are specific to your field of study and the subject you’re reporting on, otherwise your article might not reach the relevant audience.

2. Can You Use First Person in an Abstract?

You might think that first person is too informal for a research paper, but it’s not. Historically, writers of academic reports avoided writing in first person to uphold the formality standards of the time. However, first person is more accepted in research papers in modern times.

If you’re still unsure whether to write in first person for your abstract, refer to any style guide rules imposed by the journal you’re writing for or your teachers if you are writing an assignment.

3. Abstract Structure

Some scientific journals have strict rules on how to structure an abstract, so it’s best to check those first. If you don’t have any style rules to follow, try using the IMRaD structure, which stands for Introduction, Methodology, Results, and Discussion.

Following the IMRaD structure, start with an introduction. The amount of background information you should include depends on your specific research area. Adding a broad overview gives you less room to include other details. Remember to include your hypothesis in this section.

The next part of your abstract should cover your methodology. Try to include the following details if they apply to your study:

What type of research was conducted?

How were the test subjects sampled?

What were the sample sizes?

What was done to each group?

How long was the experiment?

How was data recorded and interpreted?

Following the methodology, include a sentence or two about the results, which is where your reader will determine if your research supports or contradicts their own investigations.

The results are also where most people will want to find out what your outcomes were, even if they are just mildly interested in your research area. You should be specific about all the details but as concise as possible.

The last few sentences are your conclusion. It needs to explain how your findings affect the context and whether your hypothesis was correct. Include the primary take-home message, additional findings of importance, and perspective. Also explain whether there is scope for further research into the subject of your report.

Your conclusion should be honest and give the reader the ultimate message that your research shows. Readers trust the conclusion, so make sure you’re not fabricating the results of your research. Some readers won’t read your entire paper, but this section will tell them if it’s worth them referencing it in their own study.

4. How to Start an Abstract

The first line of your abstract should give your reader the context of your report by providing background information. You can use this sentence to imply the motivation for your research.

You don’t need to use a hook phrase or device in your first sentence to grab the reader’s attention. Your reader will look to establish relevance quickly, so readability and clarity are more important than trying to persuade the reader to read on.

5. How to Format an Abstract

Most abstracts use the same formatting rules, which help the reader identify the abstract so they know where to look for it.

Here’s a list of formatting guidelines for writing an abstract:

Stick to one paragraph

Use block formatting with no indentation at the beginning

Put your abstract straight after the title and acknowledgements pages

Use present or past tense, not future tense

There are two primary types of abstract you could write for your paper—descriptive and informative.

An informative abstract is the most common, and they follow the structure mentioned previously. They are longer than descriptive abstracts because they cover more details.

Descriptive abstracts differ from informative abstracts, as they don’t include as much discussion or detail. The word count for a descriptive abstract is between 50 and 150 words.

Here is an example of an informative abstract:

A growing trend exists for authors to employ a more informal writing style that uses “we” in academic writing to acknowledge one’s stance and engagement. However, few studies have compared the ways in which the first-person pronoun “we” is used in the abstracts and conclusions of empirical papers. To address this lacuna in the literature, this study conducted a systematic corpus analysis of the use of “we” in the abstracts and conclusions of 400 articles collected from eight leading electrical and electronic (EE) engineering journals. The abstracts and conclusions were extracted to form two subcorpora, and an integrated framework was applied to analyze and seek to explain how we-clusters and we-collocations were employed. Results revealed whether authors’ use of first-person pronouns partially depends on a journal policy. The trend of using “we” showed that a yearly increase occurred in the frequency of “we” in EE journal papers, as well as the existence of three “we-use” types in the article conclusions and abstracts: exclusive, inclusive, and ambiguous. Other possible “we-use” alternatives such as “I” and other personal pronouns were used very rarely—if at all—in either section. These findings also suggest that the present tense was used more in article abstracts, but the present perfect tense was the most preferred tense in article conclusions. Both research and pedagogical implications are proffered and critically discussed.

Wang, S., Tseng, W.-T., & Johanson, R. (2021). To We or Not to We: Corpus-Based Research on First-Person Pronoun Use in Abstracts and Conclusions. SAGE Open, 11(2).

Here is an example of a descriptive abstract:

From the 1850s to the present, considerable criminological attention has focused on the development of theoretically-significant systems for classifying crime. This article reviews and attempts to evaluate a number of these efforts, and we conclude that further work on this basic task is needed. The latter part of the article explicates a conceptual foundation for a crime pattern classification system, and offers a preliminary taxonomy of crime.

Farr, K. A., & Gibbons, D. C. (1990). Observations on the Development of Crime Categories. International Journal of Offender Therapy and Comparative Criminology, 34(3), 223–237.

If you want to ensure your abstract is grammatically correct and easy to read, you can use ProWritingAid to edit it. The software integrates with Microsoft Word, Google Docs, and most web browsers, so you can make the most of it wherever you’re writing your paper.

Before you edit with ProWritingAid, make sure the suggestions you are seeing are relevant for your document by changing the document type to “Abstract” within the Academic writing style section.

You can use the Readability report to check your abstract for places to improve the clarity of your writing. Some suggestions might show you where to remove words, which is great if you’re over your word count.

We hope the five steps and examples we’ve provided help you write a great abstract for your research paper.

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• How to Write an Abstract

Expedite peer review, increase search-ability, and set the tone for your study

The abstract is your chance to let your readers know what they can expect from your article. Learn how to write a clear, and concise abstract that will keep your audience reading.

How your abstract impacts editorial evaluation and future readership

After the title , the abstract is the second-most-read part of your article. A good abstract can help to expedite peer review and, if your article is accepted for publication, it’s an important tool for readers to find and evaluate your work. Editors use your abstract when they first assess your article. Prospective reviewers see it when they decide whether to accept an invitation to review. Once published, the abstract gets indexed in PubMed and Google Scholar , as well as library systems and other popular databases. Like the title, your abstract influences keyword search results. Readers will use it to decide whether to read the rest of your article. Other researchers will use it to evaluate your work for inclusion in systematic reviews and meta-analysis. It should be a concise standalone piece that accurately represents your research. 

What to include in an abstract

The main challenge you’ll face when writing your abstract is keeping it concise AND fitting in all the information you need. Depending on your subject area the journal may require a structured abstract following specific headings. A structured abstract helps your readers understand your study more easily. If your journal doesn’t require a structured abstract it’s still a good idea to follow a similar format, just present the abstract as one paragraph without headings. 

Background or Introduction – What is currently known? Start with a brief, 2 or 3 sentence, introduction to the research area. 

Objectives or Aims – What is the study and why did you do it? Clearly state the research question you’re trying to answer.

Methods – What did you do? Explain what you did and how you did it. Include important information about your methods, but avoid the low-level specifics. Some disciplines have specific requirements for abstract methods. 

• CONSORT for randomized trials.
• STROBE for observational studies
• PRISMA for systematic reviews and meta-analyses

Results – What did you find? Briefly give the key findings of your study. Include key numeric data (including confidence intervals or p values), where possible.

Conclusions – What did you conclude? Tell the reader why your findings matter, and what this could mean for the ‘bigger picture’ of this area of research. 

Writing tips

The main challenge you may find when writing your abstract is keeping it concise AND convering all the information you need to.

• Keep it concise and to the point. Most journals have a maximum word count, so check guidelines before you write the abstract to save time editing it later.
• Write for your audience. Are they specialists in your specific field? Are they cross-disciplinary? Are they non-specialists? If you’re writing for a general audience, or your research could be of interest to the public keep your language as straightforward as possible. If you’re writing in English, do remember that not all of your readers will necessarily be native English speakers.
• Focus on key results, conclusions and take home messages.
• Write your paper first, then create the abstract as a summary.
• Check the journal requirements before you write your abstract, eg. required subheadings.
• Include keywords or phrases to help readers search for your work in indexing databases like PubMed or Google Scholar.
• Double and triple check your abstract for spelling and grammar errors. These kind of errors can give potential reviewers the impression that your research isn’t sound, and can make it easier to find reviewers who accept the invitation to review your manuscript. Your abstract should be a taste of what is to come in the rest of your article.

Don’t

• Sensationalize your research.
• Speculate about where this research might lead in the future.
• Use abbreviations or acronyms (unless absolutely necessary or unless they’re widely known, eg. DNA).
• Repeat yourself unnecessarily, eg. “Methods: We used X technique. Results: Using X technique, we found…”
• Contradict anything in the rest of your manuscript.
• Include content that isn’t also covered in the main manuscript.
• Include citations or references.

Tip: How to edit your work

Editing is challenging, especially if you are acting as both a writer and an editor. Read our guidelines for advice on how to refine your work, including useful tips for setting your intentions, re-review, and consultation with colleagues.

• How to Write a Great Title
• How to Write Your Methods
• How to Report Statistics
• How to Write Discussions and Conclusions
• How to Edit Your Work

The contents of the Peer Review Center are also available as a live, interactive training session, complete with slides, talking points, and activities. …

The contents of the Writing Center are also available as a live, interactive training session, complete with slides, talking points, and activities. …

There’s a lot to consider when deciding where to submit your work. Learn how to choose a journal that will help your study reach its audience, while reflecting your values as a researcher…

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• How to Write an Abstract | Steps & Examples

How to Write an Abstract | Steps & Examples

Published on 1 March 2019 by Shona McCombes . Revised on 10 October 2022 by Eoghan Ryan.

An abstract is a short summary of a longer work (such as a dissertation or research paper ). The abstract concisely reports the aims and outcomes of your research, so that readers know exactly what your paper is about.

Although the structure may vary slightly depending on your discipline, your abstract should describe the purpose of your work, the methods you’ve used, and the conclusions you’ve drawn.

One common way to structure your abstract is to use the IMRaD structure. This stands for:

• Introduction

Abstracts are usually around 100–300 words, but there’s often a strict word limit, so make sure to check the relevant requirements.

In a dissertation or thesis , include the abstract on a separate page, after the title page and acknowledgements but before the table of contents .

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Table of contents

Abstract example, when to write an abstract, step 1: introduction, step 2: methods, step 3: results, step 4: discussion, tips for writing an abstract, frequently asked questions about abstracts.

Hover over the different parts of the abstract to see how it is constructed.

This paper examines the role of silent movies as a mode of shared experience in the UK during the early twentieth century. At this time, high immigration rates resulted in a significant percentage of non-English-speaking citizens. These immigrants faced numerous economic and social obstacles, including exclusion from public entertainment and modes of discourse (newspapers, theater, radio).

Incorporating evidence from reviews, personal correspondence, and diaries, this study demonstrates that silent films were an affordable and inclusive source of entertainment. It argues for the accessible economic and representational nature of early cinema. These concerns are particularly evident in the low price of admission and in the democratic nature of the actors’ exaggerated gestures, which allowed the plots and action to be easily grasped by a diverse audience despite language barriers.

Keywords: silent movies, immigration, public discourse, entertainment, early cinema, language barriers.

Prevent plagiarism, run a free check.

You will almost always have to include an abstract when:

• Completing a thesis or dissertation
• Submitting a research paper to an academic journal
• Writing a book proposal
• Applying for research grants

It’s easiest to write your abstract last, because it’s a summary of the work you’ve already done. Your abstract should:

• Be a self-contained text, not an excerpt from your paper
• Be fully understandable on its own
• Reflect the structure of your larger work

Start by clearly defining the purpose of your research. What practical or theoretical problem does the research respond to, or what research question did you aim to answer?

You can include some brief context on the social or academic relevance of your topic, but don’t go into detailed background information. If your abstract uses specialised terms that would be unfamiliar to the average academic reader or that have various different meanings, give a concise definition.

After identifying the problem, state the objective of your research. Use verbs like “investigate,” “test,” “analyse,” or “evaluate” to describe exactly what you set out to do.

This part of the abstract can be written in the present or past simple tense  but should never refer to the future, as the research is already complete.

• This study will investigate the relationship between coffee consumption and productivity.
• This study investigates the relationship between coffee consumption and productivity.

Next, indicate the research methods that you used to answer your question. This part should be a straightforward description of what you did in one or two sentences. It is usually written in the past simple tense, as it refers to completed actions.

• Structured interviews will be conducted with 25 participants.
• Structured interviews were conducted with 25 participants.

Don’t evaluate validity or obstacles here — the goal is not to give an account of the methodology’s strengths and weaknesses, but to give the reader a quick insight into the overall approach and procedures you used.

Next, summarise the main research results . This part of the abstract can be in the present or past simple tense.

• Our analysis has shown a strong correlation between coffee consumption and productivity.
• Our analysis shows a strong correlation between coffee consumption and productivity.
• Our analysis showed a strong correlation between coffee consumption and productivity.

Depending on how long and complex your research is, you may not be able to include all results here. Try to highlight only the most important findings that will allow the reader to understand your conclusions.

Finally, you should discuss the main conclusions of your research : what is your answer to the problem or question? The reader should finish with a clear understanding of the central point that your research has proved or argued. Conclusions are usually written in the present simple tense.

• We concluded that coffee consumption increases productivity.
• We conclude that coffee consumption increases productivity.

If there are important limitations to your research (for example, related to your sample size or methods), you should mention them briefly in the abstract. This allows the reader to accurately assess the credibility and generalisability of your research.

If your aim was to solve a practical problem, your discussion might include recommendations for implementation. If relevant, you can briefly make suggestions for further research.

If your paper will be published, you might have to add a list of keywords at the end of the abstract. These keywords should reference the most important elements of the research to help potential readers find your paper during their own literature searches.

Be aware that some publication manuals, such as APA Style , have specific formatting requirements for these keywords.

It can be a real challenge to condense your whole work into just a couple of hundred words, but the abstract will be the first (and sometimes only) part that people read, so it’s important to get it right. These strategies can help you get started.

Read other abstracts

The best way to learn the conventions of writing an abstract in your discipline is to read other people’s. You probably already read lots of journal article abstracts while conducting your literature review —try using them as a framework for structure and style.

You can also find lots of dissertation abstract examples in thesis and dissertation databases .

Reverse outline

Not all abstracts will contain precisely the same elements. For longer works, you can write your abstract through a process of reverse outlining.

For each chapter or section, list keywords and draft one to two sentences that summarise the central point or argument. This will give you a framework of your abstract’s structure. Next, revise the sentences to make connections and show how the argument develops.

Write clearly and concisely

A good abstract is short but impactful, so make sure every word counts. Each sentence should clearly communicate one main point.

To keep your abstract or summary short and clear:

• Avoid passive sentences: Passive constructions are often unnecessarily long. You can easily make them shorter and clearer by using the active voice.
• Avoid long sentences: Substitute longer expressions for concise expressions or single words (e.g., “In order to” for “To”).
• Avoid obscure jargon: The abstract should be understandable to readers who are not familiar with your topic.
• Avoid repetition and filler words: Replace nouns with pronouns when possible and eliminate unnecessary words.
• Avoid detailed descriptions: An abstract is not expected to provide detailed definitions, background information, or discussions of other scholars’ work. Instead, include this information in the body of your thesis or paper.

If you’re struggling to edit down to the required length, you can get help from expert editors with Scribbr’s professional proofreading services .

Check your formatting

If you are writing a thesis or dissertation or submitting to a journal, there are often specific formatting requirements for the abstract—make sure to check the guidelines and format your work correctly. For APA research papers you can follow the APA abstract format .

Checklist: Abstract

The word count is within the required length, or a maximum of one page.

The abstract appears after the title page and acknowledgements and before the table of contents .

I have clearly stated my research problem and objectives.

I have briefly described my methodology .

I have summarized the most important results .

I have stated my main conclusions .

I have mentioned any important limitations and recommendations.

The abstract can be understood by someone without prior knowledge of the topic.

You've written a great abstract! Use the other checklists to continue improving your thesis or dissertation.

An abstract is a concise summary of an academic text (such as a journal article or dissertation ). It serves two main purposes:

• To help potential readers determine the relevance of your paper for their own research.
• To communicate your key findings to those who don’t have time to read the whole paper.

Abstracts are often indexed along with keywords on academic databases, so they make your work more easily findable. Since the abstract is the first thing any reader sees, it’s important that it clearly and accurately summarises the contents of your paper.

An abstract for a thesis or dissertation is usually around 150–300 words. There’s often a strict word limit, so make sure to check your university’s requirements.

The abstract is the very last thing you write. You should only write it after your research is complete, so that you can accurately summarize the entirety of your thesis or paper.

Avoid citing sources in your abstract . There are two reasons for this:

• The abstract should focus on your original research, not on the work of others.
• The abstract should be self-contained and fully understandable without reference to other sources.

There are some circumstances where you might need to mention other sources in an abstract: for example, if your research responds directly to another study or focuses on the work of a single theorist. In general, though, don’t include citations unless absolutely necessary.

The abstract appears on its own page, after the title page and acknowledgements but before the table of contents .

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the ‘Cite this Scribbr article’ button to automatically add the citation to our free Reference Generator.

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Research Paper Abstract – Writing Guide and Examples

Table of Contents

Research Paper Abstract

Research Paper Abstract is a brief summary of a research pape r that describes the study’s purpose, methods, findings, and conclusions . It is often the first section of the paper that readers encounter, and its purpose is to provide a concise and accurate overview of the paper’s content. The typical length of an abstract is usually around 150-250 words, and it should be written in a concise and clear manner.

Research Paper Abstract Structure

The structure of a research paper abstract usually includes the following elements:

• Background or Introduction: Briefly describe the problem or research question that the study addresses.
• Methods : Explain the methodology used to conduct the study, including the participants, materials, and procedures.
• Results : Summarize the main findings of the study, including statistical analyses and key outcomes.
• Conclusions : Discuss the implications of the study’s findings and their significance for the field, as well as any limitations or future directions for research.
• Keywords : List a few keywords that describe the main topics or themes of the research.

How to Write Research Paper Abstract

Here are the steps to follow when writing a research paper abstract:

• Start by reading your paper: Before you write an abstract, you should have a complete understanding of your paper. Read through the paper carefully, making sure you understand the purpose, methods, results, and conclusions.
• Identify the key components : Identify the key components of your paper, such as the research question, methods used, results obtained, and conclusion reached.
• Write a draft: Write a draft of your abstract, using concise and clear language. Make sure to include all the important information, but keep it short and to the point. A good rule of thumb is to keep your abstract between 150-250 words.
• Use clear and concise language : Use clear and concise language to explain the purpose of your study, the methods used, the results obtained, and the conclusions drawn.
• Emphasize your findings: Emphasize your findings in the abstract, highlighting the key results and the significance of your study.
• Revise and edit: Once you have a draft, revise and edit it to ensure that it is clear, concise, and free from errors.
• Check the formatting: Finally, check the formatting of your abstract to make sure it meets the requirements of the journal or conference where you plan to submit it.

Research Paper Abstract Examples

Research Paper Abstract Examples could be following:

Title : “The Effectiveness of Cognitive-Behavioral Therapy for Treating Anxiety Disorders: A Meta-Analysis”

Abstract : This meta-analysis examines the effectiveness of cognitive-behavioral therapy (CBT) in treating anxiety disorders. Through the analysis of 20 randomized controlled trials, we found that CBT is a highly effective treatment for anxiety disorders, with large effect sizes across a range of anxiety disorders, including generalized anxiety disorder, panic disorder, and social anxiety disorder. Our findings support the use of CBT as a first-line treatment for anxiety disorders and highlight the importance of further research to identify the mechanisms underlying its effectiveness.

Title : “Exploring the Role of Parental Involvement in Children’s Education: A Qualitative Study”

Abstract : This qualitative study explores the role of parental involvement in children’s education. Through in-depth interviews with 20 parents of children in elementary school, we found that parental involvement takes many forms, including volunteering in the classroom, helping with homework, and communicating with teachers. We also found that parental involvement is influenced by a range of factors, including parent and child characteristics, school culture, and socio-economic status. Our findings suggest that schools and educators should prioritize building strong partnerships with parents to support children’s academic success.

Title : “The Impact of Exercise on Cognitive Function in Older Adults: A Systematic Review and Meta-Analysis”

Abstract : This paper presents a systematic review and meta-analysis of the existing literature on the impact of exercise on cognitive function in older adults. Through the analysis of 25 randomized controlled trials, we found that exercise is associated with significant improvements in cognitive function, particularly in the domains of executive function and attention. Our findings highlight the potential of exercise as a non-pharmacological intervention to support cognitive health in older adults.

When to Write Research Paper Abstract

The abstract of a research paper should typically be written after you have completed the main body of the paper. This is because the abstract is intended to provide a brief summary of the key points and findings of the research, and you can’t do that until you have completed the research and written about it in detail.

Once you have completed your research paper, you can begin writing your abstract. It is important to remember that the abstract should be a concise summary of your research paper, and should be written in a way that is easy to understand for readers who may not have expertise in your specific area of research.

Purpose of Research Paper Abstract

The purpose of a research paper abstract is to provide a concise summary of the key points and findings of a research paper. It is typically a brief paragraph or two that appears at the beginning of the paper, before the introduction, and is intended to give readers a quick overview of the paper’s content.

The abstract should include a brief statement of the research problem, the methods used to investigate the problem, the key results and findings, and the main conclusions and implications of the research. It should be written in a clear and concise manner, avoiding jargon and technical language, and should be understandable to a broad audience.

The abstract serves as a way to quickly and easily communicate the main points of a research paper to potential readers, such as academics, researchers, and students, who may be looking for information on a particular topic. It can also help researchers determine whether a paper is relevant to their own research interests and whether they should read the full paper.

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• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 3. The Abstract
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

An abstract summarizes, usually in one paragraph of 300 words or less, the major aspects of the entire paper in a prescribed sequence that includes: 1) the overall purpose of the study and the research problem(s) you investigated; 2) the basic design of the study; 3) major findings or trends found as a result of your analysis; and, 4) a brief summary of your interpretations and conclusions.

Writing an Abstract. The Writing Center. Clarion University, 2009; Writing an Abstract for Your Research Paper. The Writing Center, University of Wisconsin, Madison; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-first Century . Oxford, UK: Chandos Publishing, 2010;

Importance of a Good Abstract

Sometimes your professor will ask you to include an abstract, or general summary of your work, with your research paper. The abstract allows you to elaborate upon each major aspect of the paper and helps readers decide whether they want to read the rest of the paper. Therefore, enough key information [e.g., summary results, observations, trends, etc.] must be included to make the abstract useful to someone who may want to examine your work.

How do you know when you have enough information in your abstract? A simple rule-of-thumb is to imagine that you are another researcher doing a similar study. Then ask yourself: if your abstract was the only part of the paper you could access, would you be happy with the amount of information presented there? Does it tell the whole story about your study? If the answer is "no" then the abstract likely needs to be revised.

Farkas, David K. “A Scheme for Understanding and Writing Summaries.” Technical Communication 67 (August 2020): 45-60;  How to Write a Research Abstract. Office of Undergraduate Research. University of Kentucky; Staiger, David L. “What Today’s Students Need to Know about Writing Abstracts.” International Journal of Business Communication January 3 (1966): 29-33; Swales, John M. and Christine B. Feak. Abstracts and the Writing of Abstracts . Ann Arbor, MI: University of Michigan Press, 2009.

Structure and Writing Style

I.  Types of Abstracts

To begin, you need to determine which type of abstract you should include with your paper. There are four general types.

Critical Abstract A critical abstract provides, in addition to describing main findings and information, a judgment or comment about the study’s validity, reliability, or completeness. The researcher evaluates the paper and often compares it with other works on the same subject. Critical abstracts are generally 400-500 words in length due to the additional interpretive commentary. These types of abstracts are used infrequently.

Descriptive Abstract A descriptive abstract indicates the type of information found in the work. It makes no judgments about the work, nor does it provide results or conclusions of the research. It does incorporate key words found in the text and may include the purpose, methods, and scope of the research. Essentially, the descriptive abstract only describes the work being summarized. Some researchers consider it an outline of the work, rather than a summary. Descriptive abstracts are usually very short, 100 words or less. Informative Abstract The majority of abstracts are informative. While they still do not critique or evaluate a work, they do more than describe it. A good informative abstract acts as a surrogate for the work itself. That is, the researcher presents and explains all the main arguments and the important results and evidence in the paper. An informative abstract includes the information that can be found in a descriptive abstract [purpose, methods, scope] but it also includes the results and conclusions of the research and the recommendations of the author. The length varies according to discipline, but an informative abstract is usually no more than 300 words in length.

Highlight Abstract A highlight abstract is specifically written to attract the reader’s attention to the study. No pretense is made of there being either a balanced or complete picture of the paper and, in fact, incomplete and leading remarks may be used to spark the reader’s interest. In that a highlight abstract cannot stand independent of its associated article, it is not a true abstract and, therefore, rarely used in academic writing.

II.  Writing Style

Use the active voice when possible , but note that much of your abstract may require passive sentence constructions. Regardless, write your abstract using concise, but complete, sentences. Get to the point quickly and always use the past tense because you are reporting on a study that has been completed.

Abstracts should be formatted as a single paragraph in a block format and with no paragraph indentations. In most cases, the abstract page immediately follows the title page. Do not number the page. Rules set forth in writing manual vary but, in general, you should center the word "Abstract" at the top of the page with double spacing between the heading and the abstract. The final sentences of an abstract concisely summarize your study’s conclusions, implications, or applications to practice and, if appropriate, can be followed by a statement about the need for additional research revealed from the findings.

Composing Your Abstract

Although it is the first section of your paper, the abstract should be written last since it will summarize the contents of your entire paper. A good strategy to begin composing your abstract is to take whole sentences or key phrases from each section of the paper and put them in a sequence that summarizes the contents. Then revise or add connecting phrases or words to make the narrative flow clearly and smoothly. Note that statistical findings should be reported parenthetically [i.e., written in parentheses].

Before handing in your final paper, check to make sure that the information in the abstract completely agrees with what you have written in the paper. Think of the abstract as a sequential set of complete sentences describing the most crucial information using the fewest necessary words. The abstract SHOULD NOT contain:

• A catchy introductory phrase, provocative quote, or other device to grab the reader's attention,
• Lengthy background or contextual information,
• Redundant phrases, unnecessary adverbs and adjectives, and repetitive information;
• Acronyms or abbreviations,
• References to other literature [say something like, "current research shows that..." or "studies have indicated..."],
• Using ellipticals [i.e., ending with "..."] or incomplete sentences,
• Jargon or terms that may be confusing to the reader,
• Citations to other works, and
• Any sort of image, illustration, figure, or table, or references to them.

Abstract. Writing Center. University of Kansas; Abstract. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Abstracts. The Writing Center. University of North Carolina; Borko, Harold and Seymour Chatman. "Criteria for Acceptable Abstracts: A Survey of Abstracters' Instructions." American Documentation 14 (April 1963): 149-160; Abstracts. The Writer’s Handbook. Writing Center. University of Wisconsin, Madison; Hartley, James and Lucy Betts. "Common Weaknesses in Traditional Abstracts in the Social Sciences." Journal of the American Society for Information Science and Technology 60 (October 2009): 2010-2018; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-first Century. Oxford, UK: Chandos Publishing, 2010; Procter, Margaret. The Abstract. University College Writing Centre. University of Toronto; Riordan, Laura. “Mastering the Art of Abstracts.” The Journal of the American Osteopathic Association 115 (January 2015 ): 41-47; Writing Report Abstracts. The Writing Lab and The OWL. Purdue University; Writing Abstracts. Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-First Century . Oxford, UK: 2010; Writing an Abstract for Your Research Paper. The Writing Center, University of Wisconsin, Madison.

Writing Tip

Never Cite Just the Abstract!

Citing to just a journal article's abstract does not confirm for the reader that you have conducted a thorough or reliable review of the literature. If the full-text is not available, go to the USC Libraries main page and enter the title of the article [NOT the title of the journal]. If the Libraries have a subscription to the journal, the article should appear with a link to the full-text or to the journal publisher page where you can get the article. If the article does not appear, try searching Google Scholar using the link on the USC Libraries main page. If you still can't find the article after doing this, contact a librarian or you can request it from our free i nterlibrary loan and document delivery service .

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What this handout is about

This handout provides definitions and examples of the two main types of abstracts: descriptive and informative. It also provides guidelines for constructing an abstract and general tips for you to keep in mind when drafting. Finally, it includes a few examples of abstracts broken down into their component parts.

What is an abstract?

An abstract is a self-contained, short, and powerful statement that describes a larger work. Components vary according to discipline. An abstract of a social science or scientific work may contain the scope, purpose, results, and contents of the work. An abstract of a humanities work may contain the thesis, background, and conclusion of the larger work. An abstract is not a review, nor does it evaluate the work being abstracted. While it contains key words found in the larger work, the abstract is an original document rather than an excerpted passage.

Why write an abstract?

You may write an abstract for various reasons. The two most important are selection and indexing. Abstracts allow readers who may be interested in a longer work to quickly decide whether it is worth their time to read it. Also, many online databases use abstracts to index larger works. Therefore, abstracts should contain keywords and phrases that allow for easy searching.

Say you are beginning a research project on how Brazilian newspapers helped Brazil’s ultra-liberal president Luiz Ignácio da Silva wrest power from the traditional, conservative power base. A good first place to start your research is to search Dissertation Abstracts International for all dissertations that deal with the interaction between newspapers and politics. “Newspapers and politics” returned 569 hits. A more selective search of “newspapers and Brazil” returned 22 hits. That is still a fair number of dissertations. Titles can sometimes help winnow the field, but many titles are not very descriptive. For example, one dissertation is titled “Rhetoric and Riot in Rio de Janeiro.” It is unclear from the title what this dissertation has to do with newspapers in Brazil. One option would be to download or order the entire dissertation on the chance that it might speak specifically to the topic. A better option is to read the abstract. In this case, the abstract reveals the main focus of the dissertation:

This dissertation examines the role of newspaper editors in the political turmoil and strife that characterized late First Empire Rio de Janeiro (1827-1831). Newspaper editors and their journals helped change the political culture of late First Empire Rio de Janeiro by involving the people in the discussion of state. This change in political culture is apparent in Emperor Pedro I’s gradual loss of control over the mechanisms of power. As the newspapers became more numerous and powerful, the Emperor lost his legitimacy in the eyes of the people. To explore the role of the newspapers in the political events of the late First Empire, this dissertation analyzes all available newspapers published in Rio de Janeiro from 1827 to 1831. Newspapers and their editors were leading forces in the effort to remove power from the hands of the ruling elite and place it under the control of the people. In the process, newspapers helped change how politics operated in the constitutional monarchy of Brazil.

From this abstract you now know that although the dissertation has nothing to do with modern Brazilian politics, it does cover the role of newspapers in changing traditional mechanisms of power. After reading the abstract, you can make an informed judgment about whether the dissertation would be worthwhile to read.

Besides selection, the other main purpose of the abstract is for indexing. Most article databases in the online catalog of the library enable you to search abstracts. This allows for quick retrieval by users and limits the extraneous items recalled by a “full-text” search. However, for an abstract to be useful in an online retrieval system, it must incorporate the key terms that a potential researcher would use to search. For example, if you search Dissertation Abstracts International using the keywords “France” “revolution” and “politics,” the search engine would search through all the abstracts in the database that included those three words. Without an abstract, the search engine would be forced to search titles, which, as we have seen, may not be fruitful, or else search the full text. It’s likely that a lot more than 60 dissertations have been written with those three words somewhere in the body of the entire work. By incorporating keywords into the abstract, the author emphasizes the central topics of the work and gives prospective readers enough information to make an informed judgment about the applicability of the work.

When do people write abstracts?

• when submitting articles to journals, especially online journals
• when applying for research grants
• when writing a book proposal
• when completing the Ph.D. dissertation or M.A. thesis
• when writing a proposal for a conference paper
• when writing a proposal for a book chapter

Most often, the author of the entire work (or prospective work) writes the abstract. However, there are professional abstracting services that hire writers to draft abstracts of other people’s work. In a work with multiple authors, the first author usually writes the abstract. Undergraduates are sometimes asked to draft abstracts of books/articles for classmates who have not read the larger work.

Types of abstracts

There are two types of abstracts: descriptive and informative. They have different aims, so as a consequence they have different components and styles. There is also a third type called critical, but it is rarely used. If you want to find out more about writing a critique or a review of a work, see the UNC Writing Center handout on writing a literature review . If you are unsure which type of abstract you should write, ask your instructor (if the abstract is for a class) or read other abstracts in your field or in the journal where you are submitting your article.

Descriptive abstracts

A descriptive abstract indicates the type of information found in the work. It makes no judgments about the work, nor does it provide results or conclusions of the research. It does incorporate key words found in the text and may include the purpose, methods, and scope of the research. Essentially, the descriptive abstract describes the work being abstracted. Some people consider it an outline of the work, rather than a summary. Descriptive abstracts are usually very short—100 words or less.

Informative abstracts

The majority of abstracts are informative. While they still do not critique or evaluate a work, they do more than describe it. A good informative abstract acts as a surrogate for the work itself. That is, the writer presents and explains all the main arguments and the important results and evidence in the complete article/paper/book. An informative abstract includes the information that can be found in a descriptive abstract (purpose, methods, scope) but also includes the results and conclusions of the research and the recommendations of the author. The length varies according to discipline, but an informative abstract is rarely more than 10% of the length of the entire work. In the case of a longer work, it may be much less.

Here are examples of a descriptive and an informative abstract of this handout on abstracts . Descriptive abstract:

The two most common abstract types—descriptive and informative—are described and examples of each are provided.

Informative abstract:

Abstracts present the essential elements of a longer work in a short and powerful statement. The purpose of an abstract is to provide prospective readers the opportunity to judge the relevance of the longer work to their projects. Abstracts also include the key terms found in the longer work and the purpose and methods of the research. Authors abstract various longer works, including book proposals, dissertations, and online journal articles. There are two main types of abstracts: descriptive and informative. A descriptive abstract briefly describes the longer work, while an informative abstract presents all the main arguments and important results. This handout provides examples of various types of abstracts and instructions on how to construct one.

Which type should I use?

Your best bet in this case is to ask your instructor or refer to the instructions provided by the publisher. You can also make a guess based on the length allowed; i.e., 100-120 words = descriptive; 250+ words = informative.

How do I write an abstract?

The format of your abstract will depend on the work being abstracted. An abstract of a scientific research paper will contain elements not found in an abstract of a literature article, and vice versa. However, all abstracts share several mandatory components, and there are also some optional parts that you can decide to include or not. When preparing to draft your abstract, keep the following key process elements in mind:

• Reason for writing: What is the importance of the research? Why would a reader be interested in the larger work?
• Problem: What problem does this work attempt to solve? What is the scope of the project? What is the main argument/thesis/claim?
• Methodology: An abstract of a scientific work may include specific models or approaches used in the larger study. Other abstracts may describe the types of evidence used in the research.
• Results: Again, an abstract of a scientific work may include specific data that indicates the results of the project. Other abstracts may discuss the findings in a more general way.
• Implications: What changes should be implemented as a result of the findings of the work? How does this work add to the body of knowledge on the topic?

(This list of elements is adapted with permission from Philip Koopman, “How to Write an Abstract.” )

All abstracts include:

• A full citation of the source, preceding the abstract.
• The most important information first.
• The same type and style of language found in the original, including technical language.
• Key words and phrases that quickly identify the content and focus of the work.
• Clear, concise, and powerful language.

Abstracts may include:

• The thesis of the work, usually in the first sentence.
• Background information that places the work in the larger body of literature.
• The same chronological structure as the original work.

How not to write an abstract:

• Do not refer extensively to other works.
• Do not add information not contained in the original work.
• Do not define terms.

If you are abstracting your own writing

When abstracting your own work, it may be difficult to condense a piece of writing that you have agonized over for weeks (or months, or even years) into a 250-word statement. There are some tricks that you could use to make it easier, however.

Reverse outlining:

This technique is commonly used when you are having trouble organizing your own writing. The process involves writing down the main idea of each paragraph on a separate piece of paper– see our short video . For the purposes of writing an abstract, try grouping the main ideas of each section of the paper into a single sentence. Practice grouping ideas using webbing or color coding .

For a scientific paper, you may have sections titled Purpose, Methods, Results, and Discussion. Each one of these sections will be longer than one paragraph, but each is grouped around a central idea. Use reverse outlining to discover the central idea in each section and then distill these ideas into one statement.

Cut and paste:

To create a first draft of an abstract of your own work, you can read through the entire paper and cut and paste sentences that capture key passages. This technique is useful for social science research with findings that cannot be encapsulated by neat numbers or concrete results. A well-written humanities draft will have a clear and direct thesis statement and informative topic sentences for paragraphs or sections. Isolate these sentences in a separate document and work on revising them into a unified paragraph.

If you are abstracting someone else’s writing

When abstracting something you have not written, you cannot summarize key ideas just by cutting and pasting. Instead, you must determine what a prospective reader would want to know about the work. There are a few techniques that will help you in this process:

Identify key terms:

Search through the entire document for key terms that identify the purpose, scope, and methods of the work. Pay close attention to the Introduction (or Purpose) and the Conclusion (or Discussion). These sections should contain all the main ideas and key terms in the paper. When writing the abstract, be sure to incorporate the key terms.

Highlight key phrases and sentences:

Instead of cutting and pasting the actual words, try highlighting sentences or phrases that appear to be central to the work. Then, in a separate document, rewrite the sentences and phrases in your own words.

Don’t look back:

After reading the entire work, put it aside and write a paragraph about the work without referring to it. In the first draft, you may not remember all the key terms or the results, but you will remember what the main point of the work was. Remember not to include any information you did not get from the work being abstracted.

Revise, revise, revise

No matter what type of abstract you are writing, or whether you are abstracting your own work or someone else’s, the most important step in writing an abstract is to revise early and often. When revising, delete all extraneous words and incorporate meaningful and powerful words. The idea is to be as clear and complete as possible in the shortest possible amount of space. The Word Count feature of Microsoft Word can help you keep track of how long your abstract is and help you hit your target length.

Example 1: Humanities abstract

Kenneth Tait Andrews, “‘Freedom is a constant struggle’: The dynamics and consequences of the Mississippi Civil Rights Movement, 1960-1984” Ph.D. State University of New York at Stony Brook, 1997 DAI-A 59/02, p. 620, Aug 1998

This dissertation examines the impacts of social movements through a multi-layered study of the Mississippi Civil Rights Movement from its peak in the early 1960s through the early 1980s. By examining this historically important case, I clarify the process by which movements transform social structures and the constraints movements face when they try to do so. The time period studied includes the expansion of voting rights and gains in black political power, the desegregation of public schools and the emergence of white-flight academies, and the rise and fall of federal anti-poverty programs. I use two major research strategies: (1) a quantitative analysis of county-level data and (2) three case studies. Data have been collected from archives, interviews, newspapers, and published reports. This dissertation challenges the argument that movements are inconsequential. Some view federal agencies, courts, political parties, or economic elites as the agents driving institutional change, but typically these groups acted in response to the leverage brought to bear by the civil rights movement. The Mississippi movement attempted to forge independent structures for sustaining challenges to local inequities and injustices. By propelling change in an array of local institutions, movement infrastructures had an enduring legacy in Mississippi.

Now let’s break down this abstract into its component parts to see how the author has distilled his entire dissertation into a ~200 word abstract.

What the dissertation does This dissertation examines the impacts of social movements through a multi-layered study of the Mississippi Civil Rights Movement from its peak in the early 1960s through the early 1980s. By examining this historically important case, I clarify the process by which movements transform social structures and the constraints movements face when they try to do so.

How the dissertation does it The time period studied in this dissertation includes the expansion of voting rights and gains in black political power, the desegregation of public schools and the emergence of white-flight academies, and the rise and fall of federal anti-poverty programs. I use two major research strategies: (1) a quantitative analysis of county-level data and (2) three case studies.

What materials are used Data have been collected from archives, interviews, newspapers, and published reports.

Conclusion This dissertation challenges the argument that movements are inconsequential. Some view federal agencies, courts, political parties, or economic elites as the agents driving institutional change, but typically these groups acted in response to movement demands and the leverage brought to bear by the civil rights movement. The Mississippi movement attempted to forge independent structures for sustaining challenges to local inequities and injustices. By propelling change in an array of local institutions, movement infrastructures had an enduring legacy in Mississippi.

Keywords social movements Civil Rights Movement Mississippi voting rights desegregation

Example 2: Science Abstract

Luis Lehner, “Gravitational radiation from black hole spacetimes” Ph.D. University of Pittsburgh, 1998 DAI-B 59/06, p. 2797, Dec 1998

The problem of detecting gravitational radiation is receiving considerable attention with the construction of new detectors in the United States, Europe, and Japan. The theoretical modeling of the wave forms that would be produced in particular systems will expedite the search for and analysis of detected signals. The characteristic formulation of GR is implemented to obtain an algorithm capable of evolving black holes in 3D asymptotically flat spacetimes. Using compactification techniques, future null infinity is included in the evolved region, which enables the unambiguous calculation of the radiation produced by some compact source. A module to calculate the waveforms is constructed and included in the evolution algorithm. This code is shown to be second-order convergent and to handle highly non-linear spacetimes. In particular, we have shown that the code can handle spacetimes whose radiation is equivalent to a galaxy converting its whole mass into gravitational radiation in one second. We further use the characteristic formulation to treat the region close to the singularity in black hole spacetimes. The code carefully excises a region surrounding the singularity and accurately evolves generic black hole spacetimes with apparently unlimited stability.

This science abstract covers much of the same ground as the humanities one, but it asks slightly different questions.

Why do this study The problem of detecting gravitational radiation is receiving considerable attention with the construction of new detectors in the United States, Europe, and Japan. The theoretical modeling of the wave forms that would be produced in particular systems will expedite the search and analysis of the detected signals.

What the study does The characteristic formulation of GR is implemented to obtain an algorithm capable of evolving black holes in 3D asymptotically flat spacetimes. Using compactification techniques, future null infinity is included in the evolved region, which enables the unambiguous calculation of the radiation produced by some compact source. A module to calculate the waveforms is constructed and included in the evolution algorithm.

Results This code is shown to be second-order convergent and to handle highly non-linear spacetimes. In particular, we have shown that the code can handle spacetimes whose radiation is equivalent to a galaxy converting its whole mass into gravitational radiation in one second. We further use the characteristic formulation to treat the region close to the singularity in black hole spacetimes. The code carefully excises a region surrounding the singularity and accurately evolves generic black hole spacetimes with apparently unlimited stability.

Keywords gravitational radiation (GR) spacetimes black holes

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Belcher, Wendy Laura. 2009. Writing Your Journal Article in Twelve Weeks: A Guide to Academic Publishing Success. Thousand Oaks, CA: Sage Press.

Koopman, Philip. 1997. “How to Write an Abstract.” Carnegie Mellon University. October 1997. http://users.ece.cmu.edu/~koopman/essays/abstract.html .

Lancaster, F.W. 2003. Indexing And Abstracting in Theory and Practice , 3rd ed. London: Facet Publishing.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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How to Write an Abstract APA Format

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

An APA abstract is a brief, comprehensive summary of the contents of an article, research paper, dissertation, or report.

It is written in accordance with the guidelines of the American Psychological Association (APA), which is a widely used format in social and behavioral sciences. 

An APA abstract summarizes, usually in one paragraph of between 150–250 words, the major aspects of a research paper or dissertation in a prescribed sequence that includes:

• The rationale: the overall purpose of the study, providing a clear context for the research undertaken.
• Information regarding the method and participants: including materials/instruments, design, procedure, and data analysis.
• Main findings or trends: effectively highlighting the key outcomes of the hypotheses.
• Interpretations and conclusion(s): solidify the implications of the research.
• Keywords related to the study: assist the paper’s discoverability in academic databases.

The abstract should stand alone, be “self-contained,” and make sense to the reader in isolation from the main article.

The purpose of the abstract is to give the reader a quick overview of the essential information before reading the entire article. The abstract is placed on its own page, directly after the title page and before the main body of the paper.

Although the abstract will appear as the very first part of your paper, it’s good practice to write your abstract after you’ve drafted your full paper, so that you know what you’re summarizing.

Note : This page reflects the latest version of the APA Publication Manual (i.e., APA 7), released in October 2019.

Structure of the Abstract

[NOTE: DO NOT separate the components of the abstract – it should be written as a single paragraph. This section is separated to illustrate the abstract’s structure.]

1) The Rationale

One or two sentences describing the overall purpose of the study and the research problem(s) you investigated. You are basically justifying why this study was conducted.

• What is the importance of the research?
• Why would a reader be interested in the larger work?
• For example, are you filling a gap in previous research or applying new methods to take a fresh look at existing ideas or data?
• Women who are diagnosed with breast cancer can experience an array of psychosocial difficulties; however, social support, particularly from a spouse, has been shown to have a protective function during this time. This study examined the ways in which a woman’s daily mood, pain, and fatigue, and her spouse’s marital satisfaction predict the woman’s report of partner support in the context of breast cancer.
• The current nursing shortage, high hospital nurse job dissatisfaction, and reports of uneven quality of hospital care are not uniquely American phenomena.
• Students with special educational needs and disabilities (SEND) are more likely to exhibit behavioral difficulties than their typically developing peers. The aim of this study was to identify specific risk factors that influence variability in behavior difficulties among individuals with SEND.

2) The Method

Information regarding the participants (number, and population). One or two sentences outlining the method, explaining what was done and how. The method is described in the present tense.

• Pretest data from a larger intervention study and multilevel modeling were used to examine the effects of women’s daily mood, pain, and fatigue and average levels of mood, pain, and fatigue on women’s report of social support received from her partner, as well as how the effects of mood interacted with partners’ marital satisfaction.
• This paper presents reports from 43,000 nurses from more than 700 hospitals in the United States, Canada, England, Scotland, and Germany in 1998–1999.
• The study sample comprised 4,228 students with SEND, aged 5–15, drawn from 305 primary and secondary schools across England. Explanatory variables were measured at the individual and school levels at baseline, along with a teacher-reported measure of behavior difficulties (assessed at baseline and the 18-month follow-up).

3) The Results

One or two sentences indicating the main findings or trends found as a result of your analysis. The results are described in the present or past tense.

• Results show that on days in which women reported higher levels of negative or positive mood, as well as on days they reported more pain and fatigue, they reported receiving more support. Women who, on average, reported higher levels of positive mood tended to report receiving more support than those who, on average, reported lower positive mood. However, average levels of negative mood were not associated with support. Higher average levels of fatigue but not pain were associated with higher support. Finally, women whose husbands reported higher levels of marital satisfaction reported receiving more partner support, but husbands’ marital satisfaction did not moderate the effect of women’s mood on support.
• Nurses in countries with distinctly different healthcare systems report similar shortcomings in their work environments and the quality of hospital care. While the competence of and relation between nurses and physicians appear satisfactory, core problems in work design and workforce management threaten the provision of care.
• Hierarchical linear modeling of data revealed that differences between schools accounted for between 13% (secondary) and 15.4% (primary) of the total variance in the development of students’ behavior difficulties, with the remainder attributable to individual differences. Statistically significant risk markers for these problems across both phases of education were being male, eligibility for free school meals, being identified as a bully, and lower academic achievement. Additional risk markers specific to each phase of education at the individual and school levels are also acknowledged.

4) The Conclusion / Implications

A brief summary of your conclusions and implications of the results, described in the present tense. Explain the results and why the study is important to the reader.

• For example, what changes should be implemented as a result of the findings of the work?
• How does this work add to the body of knowledge on the topic?

Implications of these findings are discussed relative to assisting couples during this difficult time in their lives.

• Resolving these issues, which are amenable to managerial intervention, is essential to preserving patient safety and care of consistently high quality.
• Behavior difficulties are affected by risks across multiple ecological levels. Addressing any one of these potential influences is therefore likely to contribute to the reduction in the problems displayed.

The above examples of abstracts are from the following papers:

Aiken, L. H., Clarke, S. P., Sloane, D. M., Sochalski, J. A., Busse, R., Clarke, H., … & Shamian, J. (2001). Nurses’ reports on hospital care in five countries . Health affairs, 20(3) , 43-53.

Boeding, S. E., Pukay-Martin, N. D., Baucom, D. H., Porter, L. S., Kirby, J. S., Gremore, T. M., & Keefe, F. J. (2014). Couples and breast cancer: Women’s mood and partners’ marital satisfaction predicting support perception . Journal of Family Psychology, 28(5) , 675.

Oldfield, J., Humphrey, N., & Hebron, J. (2017). Risk factors in the development of behavior difficulties among students with special educational needs and disabilities: A multilevel analysis . British journal of educational psychology, 87(2) , 146-169.

5) Keywords

APA style suggests including a list of keywords at the end of the abstract. This is particularly common in academic articles and helps other researchers find your work in databases.

Keywords in an abstract should be selected to help other researchers find your work when searching an online database. These keywords should effectively represent the main topics of your study. Here are some tips for choosing keywords:

Core Concepts: Identify the most important ideas or concepts in your paper. These often include your main research topic, the methods you’ve used, or the theories you’re discussing.

Specificity: Your keywords should be specific to your research. For example, suppose your paper is about the effects of climate change on bird migration patterns in a specific region. In that case, your keywords might include “climate change,” “bird migration,” and the region’s name.

Consistency with Paper: Make sure your keywords are consistent with the terms you’ve used in your paper. For example, if you use the term “adolescent” rather than “teen” in your paper, choose “adolescent” as your keyword, not “teen.”

Jargon and Acronyms: Avoid using too much-specialized jargon or acronyms in your keywords, as these might not be understood or used by all researchers in your field.

Synonyms: Consider including synonyms of your keywords to capture as many relevant searches as possible. For example, if your paper discusses “post-traumatic stress disorder,” you might include “PTSD” as a keyword.

Remember, keywords are a tool for others to find your work, so think about what terms other researchers might use when searching for papers on your topic.

The Abstract SHOULD NOT contain:

Lengthy background or contextual information: The abstract should focus on your research and findings, not general topic background.

Undefined jargon, abbreviations,  or acronyms: The abstract should be accessible to a wide audience, so avoid highly specialized terms without defining them.

Citations: Abstracts typically do not include citations, as they summarize original research.

Incomplete sentences or bulleted lists: The abstract should be a single, coherent paragraph written in complete sentences.

New information not covered in the paper: The abstract should only summarize the paper’s content.

Subjective comments or value judgments: Stick to objective descriptions of your research.

Excessive details on methods or procedures: Keep descriptions of methods brief and focused on main steps.

Speculative or inconclusive statements: The abstract should state the research’s clear findings, not hypotheses or possible interpretations.

• Any illustration, figure, table, or references to them . All visual aids, data, or extensive details should be included in the main body of your paper, not in the abstract. 
• Elliptical or incomplete sentences should be avoided in an abstract . The use of ellipses (…), which could indicate incomplete thoughts or omitted text, is not appropriate in an abstract.

APA Style for Abstracts

An APA abstract must be formatted as follows:

Include the running head aligned to the left at the top of the page (professional papers only) and page number. Note, student papers do not require a running head. On the first line, center the heading “Abstract” and bold (do not underlined or italicize). Do not indent the single abstract paragraph (which begins one line below the section title). Double-space the text. Use Times New Roman font in 12 pt. Set one-inch (or 2.54 cm) margins. If you include a “keywords” section at the end of the abstract, indent the first line and italicize the word “Keywords” while leaving the keywords themselves without any formatting.

Example APA Abstract Page

Download this example as a PDF

Further Information

• APA 7th Edition Abstract and Keywords Guide
• Example APA Abstract
• How to Write a Good Abstract for a Scientific Paper or Conference Presentation
• How to Write a Lab Report
• Writing an APA paper

How long should an APA abstract be?

An APA abstract should typically be between 150 to 250 words long. However, the exact length may vary depending on specific publication or assignment guidelines. It is crucial that it succinctly summarizes the essential elements of the work, including purpose, methods, findings, and conclusions.

Where does the abstract go in an APA paper?

In an APA formatted paper, the abstract is placed on its own page, directly after the title page and before the main body of the paper. It’s typically the second page of the document. It starts with the word “Abstract” (centered and not in bold) at the top of the page, followed by the text of the abstract itself.

What are the 4 C’s of abstract writing?

The 4 C’s of abstract writing are an approach to help you create a well-structured and informative abstract. They are:

Conciseness: An abstract should briefly summarize the key points of your study. Stick to the word limit (typically between 150-250 words for an APA abstract) and avoid unnecessary details.

Clarity: Your abstract should be easy to understand. Avoid jargon and complex sentences. Clearly explain the purpose, methods, results, and conclusions of your study.

Completeness: Even though it’s brief, the abstract should provide a complete overview of your study, including the purpose, methods, key findings, and your interpretation of the results.

Cohesion: The abstract should flow logically from one point to the next, maintaining a coherent narrative about your study. It’s not just a list of disjointed elements; it’s a brief story of your research from start to finish.

What is the abstract of a psychology paper?

An abstract in a psychology paper serves as a snapshot of the paper, allowing readers to quickly understand the purpose, methodology, results, and implications of the research without reading the entire paper. It is generally between 150-250 words long.

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Writing an abstract - a six point checklist (with samples)

Posted in: abstract , dissertations

The abstract is a vital part of any research paper. It is the shop front for your work, and the first stop for your reader. It should provide a clear and succinct summary of your study, and encourage your readers to read more. An effective abstract, therefore should answer the following questions:

• Why did you do this study or project?
• What did you do and how?
• What did you find?
• What do your findings mean?

So here's our run down of the key elements of a well-written abstract.

• Size - A succinct and well written abstract should be between approximately 100- 250 words.
• Background - An effective abstract usually includes some scene-setting information which might include what is already known about the subject, related to the paper in question (a few short sentences).
• Purpose  - The abstract should also set out the purpose of your research, in other words, what is not known about the subject and hence what the study intended to examine (or what the paper seeks to present).
• Methods - The methods section should contain enough information to enable the reader to understand what was done, and how. It should include brief details of the research design, sample size, duration of study, and so on.
• Results - The results section is the most important part of the abstract. This is because readers who skim an abstract do so to learn about the findings of the study. The results section should therefore contain as much detail about the findings as the journal word count permits.
• Conclusion - This section should contain the most important take-home message of the study, expressed in a few precisely worded sentences. Usually, the finding highlighted here relates to the primary outcomes of the study. However, other important or unexpected findings should also be mentioned. It is also customary, but not essential, to express an opinion about the theoretical or practical implications of the findings, or the importance of their findings for the field. Thus, the conclusions may contain three elements:
• The primary take-home message.
• Any additional findings of importance.
• Implications for future studies.

Example Abstract 2: Engineering Development and validation of a three-dimensional finite element model of the pelvic bone.

Abstract from: Dalstra, M., Huiskes, R. and Van Erning, L., 1995. Development and validation of a three-dimensional finite element model of the pelvic bone. Journal of biomechanical engineering, 117(3), pp.272-278.

And finally...  A word on abstract types and styles

Abstract types can differ according to subject discipline. You need to determine therefore which type of abstract you should include with your paper. Here are two of the most common types with examples.

Informative Abstract

The majority of abstracts are informative. While they still do not critique or evaluate a work, they do more than describe it. A good informative abstract acts as a surrogate for the work itself. That is, the researcher presents and explains all the main arguments and the important results and evidence in the paper. An informative abstract includes the information that can be found in a descriptive abstract [purpose, methods, scope] but it also includes the results and conclusions of the research and the recommendations of the author. The length varies according to discipline, but an informative abstract is usually no more than 300 words in length.

Descriptive Abstract A descriptive abstract indicates the type of information found in the work. It makes no judgements about the work, nor does it provide results or conclusions of the research. It does incorporate key words found in the text and may include the purpose, methods, and scope of the research. Essentially, the descriptive abstract only describes the work being summarised. Some researchers consider it an outline of the work, rather than a summary. Descriptive abstracts are usually very short, 100 words or less.

Adapted from Andrade C. How to write a good abstract for a scientific paper or conference presentation. Indian J Psychiatry. 2011 Apr;53(2):172-5. doi: 10.4103/0019-5545.82558. PMID: 21772657; PMCID: PMC3136027 .

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How to Write an Abstract for a Research Paper | Examples

What is a research paper abstract?

Research paper abstracts summarize your study quickly and succinctly to journal editors and researchers and prompt them to read further. But with the ubiquity of online publication databases, writing a compelling abstract is even more important today than it was in the days of bound paper manuscripts.

Abstracts exist to “sell”  your work, and they could thus be compared to the “executive summary” of a business resume: an official briefing on what is most important about your research. Or the “gist” of your research. With the majority of academic transactions being conducted online, this means that you have even less time to impress readers–and increased competition in terms of other abstracts out there to read.

The APCI (Academic Publishing and Conferences International) notes that there are  12 questions or “points” considered in the selection process  for journals and conferences and stresses the importance of having an abstract that ticks all of these boxes. Because it is often the ONLY chance you have to convince readers to keep reading, it is important that you spend time and energy crafting an abstract that faithfully represents the central parts of your study and captivates your audience.

With that in mind, follow these suggestions when structuring and writing your abstract, and learn how exactly to put these ideas into a solid abstract that will captivate your target readers.

Before Writing Your Abstract

How long should an abstract be.

All abstracts are written with the same essential objective: to give a summary of your study. But there are two basic styles of abstract: descriptive and informative . Here is a brief delineation of the two:

Of the two types of abstracts, informative abstracts are much more common, and they are widely used for submission to journals and conferences. Informative abstracts apply to lengthier and more technical research and are common in the sciences, engineering, and psychology, while descriptive abstracts are more likely used in humanities and social science papers. The best method of determining which abstract type you need to use is to follow the instructions for journal submissions and to read as many other published articles in those journals as possible.

Research Abstract Guidelines and Requirements

As any article about research writing will tell you, authors must always closely follow the specific guidelines and requirements indicated in the Guide for Authors section of their target journal’s website. The same kind of adherence to conventions should be applied to journal publications, for consideration at a conference, and even when completing a class assignment.

Each publisher has particular demands when it comes to formatting and structure. Here are some common questions addressed in the journal guidelines:

• Is there a maximum or minimum word/character length?
• What are the style and formatting requirements?
• What is the appropriate abstract type?
• Are there any specific content or organization rules that apply?

There are of course other rules to consider when composing a research paper abstract. But if you follow the stated rules the first time you submit your manuscript, you can avoid your work being thrown in the “circular file” right off the bat.

Identify Your Target Readership

The main purpose of your abstract is to lead researchers to the full text of your research paper. In scientific journals, abstracts let readers decide whether the research discussed is relevant to their own interests or study. Abstracts also help readers understand your main argument quickly. Consider these questions as you write your abstract:

• Are other academics in your field the main target of your study?
• Will your study perhaps be useful to members of the general public?
• Do your study results include the wider implications presented in the abstract?

Outlining and Writing Your Abstract

What to include in an abstract.

Just as your  research paper title  should cover as much ground as possible in a few short words, your abstract must cover  all  parts of your study in order to fully explain your paper and research. Because it must accomplish this task in the space of only a few hundred words, it is important not to include ambiguous references or phrases that will confuse the reader or mislead them about the content and objectives of your research. Follow these  dos  and  don’ts  when it comes to what kind of writing to include:

• Avoid acronyms or abbreviations since these will need to be explained in order to make sense to the reader, which takes up valuable abstract space. Instead, explain these terms in the Introduction section of the main text.
• Only use references to people or other works if they are well-known. Otherwise, avoid referencing anything outside of your study in the abstract.
• Never include tables, figures, sources, or long quotations in your abstract; you will have plenty of time to present and refer to these in the body of your paper.

Use keywords in your abstract to focus your topic

A vital search tool is the research paper keywords section, which lists the most relevant terms directly underneath the abstract. Think of these keywords as the “tubes” that readers will seek and enter—via queries on databases and search engines—to ultimately land at their destination, which is your paper. Your abstract keywords should thus be words that are commonly used in searches but should also be highly relevant to your work and found in the text of your abstract. Include 5 to 10 important words or short phrases central to your research in both the abstract and the keywords section.

For example, if you are writing a paper on the prevalence of obesity among lower classes that crosses international boundaries, you should include terms like “obesity,” “prevalence,” “international,” “lower classes,” and “cross-cultural.” These are terms that should net a wide array of people interested in your topic of study. Look at our nine rules for choosing keywords for your research paper if you need more input on this.

Research Paper Abstract Structure

As mentioned above, the abstract (especially the informative abstract) acts as a surrogate or synopsis of your research paper, doing almost as much work as the thousands of words that follow it in the body of the main text. In the hard sciences and most social sciences, the abstract includes the following sections and organizational schema.

Each section is quite compact—only a single sentence or two, although there is room for expansion if one element or statement is particularly interesting or compelling. As the abstract is almost always one long paragraph, the individual sections should naturally merge into one another to create a holistic effect. Use the following as a checklist to ensure that you have included all of the necessary content in your abstract.

1) Identify your purpose and motivation

So your research is about rabies in Brazilian squirrels. Why is this important? You should start your abstract by explaining why people should care about this study—why is it significant to your field and perhaps to the wider world? And what is the exact purpose of your study; what are you trying to achieve? Start by answering the following questions:

• What made you decide to do this study or project?
• Why is this study important to your field or to the lay reader?
• Why should someone read your entire article?

In summary, the first section of your abstract should include the importance of the research and its impact on related research fields or on the wider scientific domain.

2) Explain the research problem you are addressing

Stating the research problem that your study addresses is the corollary to why your specific study is important and necessary. For instance, even if the issue of “rabies in Brazilian squirrels” is important, what is the problem—the “missing piece of the puzzle”—that your study helps resolve?

You can combine the problem with the motivation section, but from a perspective of organization and clarity, it is best to separate the two. Here are some precise questions to address:

• What is your research trying to better understand or what problem is it trying to solve?
• What is the scope of your study—does it try to explain something general or specific?
• What is your central claim or argument?

3) Discuss your research approach

Your specific study approach is detailed in the Methods and Materials section .  You have already established the importance of the research, your motivation for studying this issue, and the specific problem your paper addresses. Now you need to discuss  how  you solved or made progress on this problem—how you conducted your research. If your study includes your own work or that of your team, describe that here. If in your paper you reviewed the work of others, explain this here. Did you use analytic models? A simulation? A double-blind study? A case study? You are basically showing the reader the internal engine of your research machine and how it functioned in the study. Be sure to:

• Detail your research—include methods/type of the study, your variables, and the extent of the work
• Briefly present evidence to support your claim
• Highlight your most important sources

4) Briefly summarize your results

Here you will give an overview of the outcome of your study. Avoid using too many vague qualitative terms (e.g, “very,” “small,” or “tremendous”) and try to use at least some quantitative terms (i.e., percentages, figures, numbers). Save your qualitative language for the conclusion statement. Answer questions like these:

• What did your study yield in concrete terms (e.g., trends, figures, correlation between phenomena)?
• How did your results compare to your hypothesis? Was the study successful?
• Where there any highly unexpected outcomes or were they all largely predicted?

5) State your conclusion

In the last section of your abstract, you will give a statement about the implications and  limitations of the study . Be sure to connect this statement closely to your results and not the area of study in general. Are the results of this study going to shake up the scientific world? Will they impact how people see “Brazilian squirrels”? Or are the implications minor? Try not to boast about your study or present its impact as  too  far-reaching, as researchers and journals will tend to be skeptical of bold claims in scientific papers. Answer one of these questions:

• What are the exact effects of these results on my field? On the wider world?
• What other kind of study would yield further solutions to problems?
• What other information is needed to expand knowledge in this area?

After Completing the First Draft of Your Abstract

Revise your abstract.

The abstract, like any piece of academic writing, should be revised before being considered complete. Check it for  grammatical and spelling errors  and make sure it is formatted properly.

Get feedback from a peer

Getting a fresh set of eyes to review your abstract is a great way to find out whether you’ve summarized your research well. Find a reader who understands research papers but is not an expert in this field or is not affiliated with your study. Ask your reader to summarize what your study is about (including all key points of each section). This should tell you if you have communicated your key points clearly.

In addition to research peers, consider consulting with a professor or even a specialist or generalist writing center consultant about your abstract. Use any resource that helps you see your work from another perspective.

Consider getting professional editing and proofreading

While peer feedback is quite important to ensure the effectiveness of your abstract content, it may be a good idea to find an academic editor  to fix mistakes in grammar, spelling, mechanics, style, or formatting. The presence of basic errors in the abstract may not affect your content, but it might dissuade someone from reading your entire study. Wordvice provides English editing services that both correct objective errors and enhance the readability and impact of your work.

Additional Abstract Rules and Guidelines

Write your abstract after completing your paper.

Although the abstract goes at the beginning of your manuscript, it does not merely introduce your research topic (that is the job of the title), but rather summarizes your entire paper. Writing the abstract last will ensure that it is complete and consistent with the findings and statements in your paper.

Keep your content in the correct order

Both questions and answers should be organized in a standard and familiar way to make the content easier for readers to absorb. Ideally, it should mimic the overall format of your essay and the classic “introduction,” “body,” and “conclusion” form, even if the parts are not neatly divided as such.

Write the abstract from scratch

Because the abstract is a self-contained piece of writing viewed separately from the body of the paper, you should write it separately as well. Never copy and paste direct quotes from the paper and avoid paraphrasing sentences in the paper. Using new vocabulary and phrases will keep your abstract interesting and free of redundancies while conserving space.

Don’t include too many details in the abstract

Again, the density of your abstract makes it incompatible with including specific points other than possibly names or locations. You can make references to terms, but do not explain or define them in the abstract. Try to strike a balance between being specific to your study and presenting a relatively broad overview of your work.

Wordvice Resources

If you think your abstract is fine now but you need input on abstract writing or require English editing services (including paper editing ), then head over to the Wordvice academic resources page, where you will find many more articles, for example on writing the Results , Methods , and Discussion sections of your manuscript, on choosing a title for your paper , or on how to finalize your journal submission with a strong cover letter .    

Apr 27, 2024

How to Write an Abstract for Your Research Paper

Did you know that many people decide whether or not to read your entire research paper based on the abstract alone? Make sure yours packs a punch!

This guide will break down the elements of an effective abstract, helping you showcase your research and attract the right readership.

Purpose of an Abstract

Think of your abstract as a multi-purpose tool:

Snapshot for Readers:

Quick Overview: Potential readers can get the gist of your research (problem, methods, results, significance) in a matter of minutes.

Decision-Making Tool: They can quickly decide if your paper goes deep enough into their area of interest to warrant reading it in full.

Discoverability Beacon:

Keywords: Strategic keywords increase the chance of your paper appearing in relevant database searches.

Indexing: Abstracts play a role in how journals index your research, improving its visibility within your field.

Crafting a Research Paper Abstract

While brief, a well-written abstract packs a punch. Here's what to include:

Research Problem: Briefly state the question, issue, or gap in knowledge that your research addresses.

Methodology : Summarize your approach in a sentence or two (e.g., experimental design, survey, qualitative analysis).

Main Results: Highlight your most important findings or key discoveries.

Conclusion/Significance: Concisely explain the impact or implications of your findings for the field.

Be Specific: Avoid vague or overly general statements.

Self-Contained: A reader should understand the abstract without having read the whole paper.

Word Count Matters: Follow any guidelines on word limits (typically around 150-250 words).

IMPORTANT: Abstracts often have strict formatting requirements (no citations, headings, etc.). Always consult the specific instructions from your instructor or publication.

Types of Abstracts

The two primary types of abstracts differ in their level of detail:

Descriptive Abstract

Purpose: Outlines the main purpose, scope, and focus of your research.

Omissions: Does NOT include specific results, conclusions, or recommendations.

Best For: Papers where the research question and methodology are the most interesting, or when the findings are complex and would be overwhelming to fully summarize in a short abstract.

Informative Abstract

Purpose: Acts as a mini version of your paper, including all major elements.

Includes: Problem statement, methods, key results, conclusions, and potential implications.

Best For: Empirical studies with straightforward results and clear conclusions, or papers where the findings are themselves the main contribution.

How to Write Each Type

Descriptive Abstract:

State the research problem/question

Briefly outline your methods

Highlight the type of data examined or the theoretical perspective used

Indicate the scope or focus of the research

All the elements of the descriptive abstract

Succinctly present your key findings

Conclude with significance or recommendations

Is an Informative Abstract Suitable for All Types of Research Papers?

No. Here's why:

Length: Informative abstracts can become lengthy. Some publications have stricter word limits.

Complexity: Papers with nuanced results or less conclusive findings might be better served by a descriptive abstract that focuses on the motivation of the research.

Audience: Consider who the likely readers are. A highly specialized audience might appreciate a detailed informative abstract, while a wider readership might find a descriptive abstract less intimidating.

Note: Always follow guidelines provided by your instructor or target publication. Some disciplines have strong preferences for one type of abstract over the other.

Structuring Your Abstract

While there's no single "perfect" structure, a common approach is to mirror the organization of the paper itself, presenting elements in a condensed form:

Problem Statement (1-2 sentences): Clearly outline the research question, the gap in the literature, or the specific issue addressed.

Methodology (1-2 sentences): Briefly describe the approach (experimental design, survey type, qualitative methodology, etc.).

Results (2-3 sentences): Present your most important or significant findings.

Conclusion/Significance (1-2 sentences): Summarize the main takeaway and the implications of your work for the field.

Should an Abstract Always Follow a Standard Structure?

No. While a standard structure provides familiarity, prioritizing the most compelling aspects of your research is key. Consider:

Groundbreaking Results: If your findings offer a significant breakthrough, it may be worth leading with those to immediately capture attention, even if it means slightly deviating from the standard structure.

Unique Methodology: If your research employs a novel or innovative methodology, highlighting this upfront can draw in readers intrigued by your approach.

Key Components to Include

While the order might shift slightly, make sure you touch on all of these:

Purpose: The "why" of your research. What were you aiming to achieve?

Method: How did you go about answering your question or exploring the issue?

Results: What did you find? (This should be the most substantial part of your abstract)

Significance: Why does your research matter? What does it contribute to the field?

Adapt Based on Type: A descriptive abstract might omit specific results, while an informative one must have them.

Word Count Matters: Strive for conciseness. Avoid wordiness or unnecessary jargon.

Abstract Writing Tips

Write it Last: It's often easier to write a strong abstract once you've finished your paper and can distill the most important points.

Keywords Carefully: Choose keywords that accurately reflect your research focus to increase discoverability in databases.

Get Feedback: Ask a peer, instructor, or mentor to read your abstract. They can ensure it makes sense even to someone unfamiliar with your specific topic.

Revise, Revise, Revise: Don't settle for your first draft. Refine your word choices for clarity and maximum impact within the word limit.

Avoiding Common Pitfalls

Too Much Jargon: Keep your language accessible to a broader audience within your field. Overuse of discipline-specific terminology can make your work seem inaccessible.

Excessive Detail: An abstract should entice the reader to explore your full paper for the details. Don't try to cram everything in.

Vagueness: Use specific terms and phrases. Avoid generic statements that could apply to any research paper.

Introducing New Material: Your abstract should summarize existing content from your paper, not introduce entirely new arguments or data.

Can Using Technical Jargon in an Abstract Benefit the Reader's Understanding?

Rarely. Here's why excessive jargon is detrimental:

Alienates Readers: Even within a field, readers have varying levels of specialization. Jargon creates a barrier and might discourage potential readers who could otherwise benefit from your work.

Obscures the Core Ideas: Jargon sometimes masks imprecise thinking. Plain language forces you to articulate complex concepts clearly.

Limits Reach: Using accessible language makes your research discoverable by a wider audience, potentially increasing citations and sparking interdisciplinary discussions.

When Jargon is Necessary:

Define Your Terms: If a technical term is unavoidable, provide a brief, clear definition the first time it's used.

Strike a Balance: Maintain a focus on readability while showcasing your grasp of the field's terminology.

Evaluating Abstract Quality

Ask yourself these key questions:

Does it accurately reflect the paper? Anyone reading your abstract should have a clear idea of what your full paper will contain, with no misleading promises.

Is it self-contained? The abstract should make sense on its own, without forcing the reader to consult your paper for clarification.

Is it engaging? Does your opening sentence grab attention? Does the abstract leave the reader curious to learn more?

Is it free of errors? A polished abstract signals attention to detail and professionalism. Proofread carefully!

Does it follow guidelines? Adherence to word limits and any formatting requirements mandated by your instructor or publisher is essential.

How Abstract Quality Impacts Reception

Your abstract has these important functions:

Gatekeeper: Researchers will often decide whether to read your full paper based on the abstract alone. A weak abstract means lost potential readers.

Search Optimizer: Your abstract, with its keywords, plays a crucial role in whether your paper surfaces when people search databases relevant to your field.

First Impression: The abstract sets the reader's expectations for the entire paper. A well-crafted abstract creates a positive anticipation for your work.

Feedback and Revisions

Here's how to strategically use feedback:

Multiple Readers: Get feedback from people with varying levels of familiarity with your topic. This helps you assess clarity for a wider audience.

Specific Questions: Ask your reviewers:

Did the abstract make you want to read the full paper?

Were any parts confusing or overly technical?

Does it accurately represent the paper's focus and conclusions?

Open to Change: Don't be afraid to significantly revise your abstract based on feedback. Sometimes a fresh opening sentence or rephrased result statement makes a world of difference.

Conclusion: Perfecting the Research Paper Abstract

Your abstract serves as a beacon, guiding readers to the heart of your research. It's a testament to the rigor of your study and a testament to your ability to synthesize complex ideas into a concise, compelling format. By carefully crafting your abstract, you showcase the following:

Understanding of Your Work: An effective abstract demonstrates that you have a strong grasp of your own research, its purpose, methodology, and key findings.

Communicative Clarity: The ability to articulate your research succinctly is a valuable skill across academic and professional settings.

Respect for Your Audience: A well-written abstract makes your work accessible to a broader readership, maximizing its potential impact within your field.

Remember, your abstract is often the first, and sometimes the only, encounter a potential reader will have with your research. Invest time and effort into refining this crucial component. In doing so, you open doors for meaningful engagement with your work, invite collaboration, and propel both your own scholarship and the broader scholarly landscape forward.

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• Open access
• Published: 18 April 2024

Largest known madtsoiid snake from warm Eocene period of India suggests intercontinental Gondwana dispersal

• Debajit Datta   ORCID: orcid.org/0000-0001-6078-9830 1 &
• Sunil Bajpai   ORCID: orcid.org/0000-0002-2279-445X 1  

Scientific Reports volume  14 , Article number:  8054 ( 2024 ) Cite this article

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• Palaeontology

Here we report the discovery of fossils representing partial vertebral column of a giant madtsoiid snake from an early Middle Eocene (Lutetian, ~ 47 Ma) lignite-bearing succession in Kutch, western India. The estimated body length of ~ 11–15 m makes this new taxon ( Vasuki indicus gen et sp. nov.) the largest known madtsoiid snake, which thrived during a warm geological interval with average temperatures estimated at ~ 28 °C. Phylogenetically, Vasuki forms a distinct clade with the Indian Late Cretaceous taxon Madtsoia pisdurensis and the North African Late Eocene Gigantophis garstini . Biogeographic considerations, seen in conjunction with its inter-relationship with other Indian and North African madtsoiids, suggest that Vasuki represents a relic lineage that originated in India. Subsequent India-Asia collision at ~ 50 Ma led to intercontinental dispersal of this lineage from the subcontinent into North Africa through southern Eurasia.

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Introduction.

Madtsoiidae are an extinct clade of primarily Gondwanan terrestrial snakes with a temporal range spanning about 100 Myr from the Late Cretaceous–Late Pleistocene 1 , 2 , 3 . Their geographic range during the Late Cretaceous encompassed Madagascar, South America, India, Africa and the European archipelago 1 , 4 , 5 , 6 , 7 , 8 , 9 . The Cenozoic forms are restricted to North Africa, South America, the Indian subcontinent and Australia 2 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 . Madtsoiids display a broad spectrum of body-sizes and include some of the largest known terrestrial snakes that ever lived 2 , 7 , 9 . Although a speciose clade, most taxa are known exclusively from vertebrae, resulting in poorly constrained in-group relationships 2 , 8 , 16 . Additionally, the phylogenetic position of Madtsoiidae within Ophidia has remained contentious, as some studies recover it within Serpentes whereas others place it outside the crown group 3 , 9 , 17 , 18 , 19 , 20 . These phylogenetic uncertainties have hampered our understanding of madtsoiid biogeography and radiation events 2 , 8 .

In the Indian subcontinent, Late Cretaceous (Maastrichtian) madtsoiids are known from the Deccan volcanic province, including the large-sized Madtsoia pisdurensis from the Lameta Formation 6 , 8 . Among Tertiary madtsoiids, indeterminate forms are known from the early Paleocene Khadro Formation (Pakistan 16 ) and the early Eocene Cambay Shale (India 15 ). The latter also yielded the large madtsoiid Platyspondylophis 21 . The Eocene and Late Oligocene records include indeterminate taxa from Kutch and Ladakh, respectively 14 , 22 . Here we report the discovery of a giant madtsoiid snake, one of largest snakes ever reported, from an interval corresponding to a warm Middle Eocene period (~ 47 Ma) of India. Fossils were collected from an early Lutetian grey shale unit from Panandhro Lignite Mine, Kutch, Gujrat State, western India (Supplementary Note 1 , Fig.  1 ), and includes an excellently preserved, partial vertebral column. The discovery of a giant Eocene snake has important implications for madtsoiid biogeography in the context of Gondwanan inter-continental dispersal, and the evolution of large body-sizes possibly driven by high temperatures in the Middle Eocene tropical zones.

Geological map of Kutch Basin showing fossil locality ( a ); stratigraphic column at Panandhro Lignite Mine showing the position of madtsoiid snake-yielding horizon with age diagnostic dinoflagellate cyst assemblage and δ 13 C curve marking hyperthermal event ETM2 (modified after Agrawal et al. 23 ) ( b ); panoramic view of the fossil site ( c ). Map and stratigraphic column were drawn by D.D. using CorelDRAW 2019 (Version number: 21.0.0.593, URL link: http://www.corel.com/en/ ). ETM2 age estimate after Westerhold et al. 24 .

Systematic paleontology

Squamata Oppel, 1811

Ophidia Brongniart, 1800

Madtsoiidae (Hoffstetter 1961) McDowell, 1987

Vasuki indicus gen. et sp. nov.

Generic name after the well-known Hindu mythical serpent ‘Vāsuki’ around the neck of Lord Shiva; specific name is for the country of origin i.e., India.

IITR/VPL/SB 3102-1-21; a partial vertebral column representing the precloacal region (Figs. 2 , 3 ; Supplementary Table 1 ).

Anterior trunk vertebrae of Vasuki indicus . IITR/VPL/SB 3102-3, partial vertebra in anterior view ( a ); posterior view ( b ); left lateral view ( c ); dorsal view ( d ); ventral view ( e ). IITR/VPL/SB 3102-5, complete vertebra in anterior view ( f ); posterior view ( g ); left lateral view ( h ); dorsal view ( i ); ventral view ( j ). IITR/VPL/SB 3102-7I-II, partial vertebra in anterior view ( k ); posterior view; ( l ); left lateral view ( m ); dorsal view ( n ); ventral view ( o ). IITR/VPL/SB 3102-6, complete posterior anterior trunk vertebra in anterior view ( p ); posterior view ( q ); left lateral view ( r ); dorsal view ( s ); ventral view ( t ). Grey arrows indicate anterior direction. Red arrowheads and arrows indicate fossae on neural spinal base and endozygantral foramina, respectively. Roman numerals on figures ( m–o ) refer to individual vertebrae in articulated specimens where ‘I” is towards the anterior. White arrowhead and arrow indicate fossa medial to diapophysis and foramen on dorsal surface of neural arch. co cotyle, cn condyle, da diapophysis, hyp hypapophysis, izr interzygapophyseal ridge, msf median shaft, nc neural canal, nrl neural arch lamina, ns neural spine, pa parapophysis, pcof paracotylar foramen, pcofo paracotylar fossa, pcon paracotylar notch, po postzygapophysis, pr prezygapophysis, psl prespinal lamina, pzgf parazygantral foramen, pzgfo parazygantral fossa, scf subcentral foramen, scfo subcentral fossa, zg zygantrum, zs zygosphene. Scale bar represents 50 mm.

Precloacal vertebrae of Vasuki indicus . IITR/VPL/SB 3102-10I-II, complete posterior anterior trunk/mid-trunk vertebrae in anterior view ( a ); posterior view ( b ); right lateral view ( c ); dorsal view ( d ); ventral view ( e ). IITR/VPL/SB 3102-9I-II, partial mid-trunk vertebrae in anterior view ( f ); posterior view ( g ); left lateral (reversed) view ( h ); dorsal view ( i ); ventral view ( j ). IITR/VPL/SB 3102-4, nearly-complete mid-trunk vertebra in anterior view ( k ); posterior view; ( l ); left lateral (reversed) view ( m ); dorsal view ( n ); ventral view ( o ). IITR/VPL/SB 3102-8I-II, partial mid-trunk vertebrae in anterior view ( p ); posterior view ( q ); right lateral view ( r ); dorsal view ( s ); ventral view ( t ). IITR/VPL/SB 3102-11I-III, partial mid-trunk vertebrae in posterior view ( u ); right lateral view ( v ); dorsal view ( w ); ventral view ( x ). Grey arrows indicate anterior direction. Roman numerals on figures ( c–e,h–j,r–t,v–w ) refer to individual vertebrae in articulated specimens where ‘I” is towards the anterior. Pink and white arrows indicate fossae and foramen on lateral surface of centrum, respectively. Red arrow indicates endozygantral foramen. White arrowheads indicate paired protuberance on ventral median shaft. co cotyle, cn condyle, da diapophysis, hyp hypapophysis, izr interzygapophyseal ridge, msf median shaft, nc neural canal, nrl neural arch lamina, ns neural spine, pa parapophysis, pcof paracotylar foramen, pcofo paracotylar fossa, po post-zygapophysis, pr prezygapophysis, psl prespinal lamina, scf subcentral foramen, scfo subcentral fossa, zg zygantrum, zs zygosphene. Scale bar represents 50 mm.

Horizon and locality

Naredi Formation; Panandhro Lignite Mine, district Kutch, Gujarat state, western India.

Vasuki exhibits a unique combination of the following characters: presence of prominent paracotylar foramina (shared with Madtsoiidae); middle-sized cotyle (shared with Madtsoiidae); median prominence on ventral margin of centrum (shared with Madtsoiidae); prezygapophyseal process absent; high angle of synapophysis with horizontal in anterior view (avg. 71.5°); MTV diapophysis level with dorsoventral midpoint of neural canal (shared with Madtsoia madagascariensis , Madtsoia camposi , Wonambi barriei and Adinophis ); prezygapophyseal buttress succeeded posteriorly by elliptical fossa (shared with Madtsoia pisdurensis ); deep V-shaped embayment (shared with Gigantophis garstini and Madtsoia pisdurensis ); oval precloacal cotyle (shared with Gigantophis garstini and Madtsoia pisdurensis ); transversely wide vertebrae (shared with Gigantophis garstini and Madtsoia pisdurensis ); neural spine posteriorly canted (shared with Gigantophis garstini and Madtsoia pisdurensis ); broad hemal keel with posterior process (shared with Gigantophis garstini and Madtsoia pisdurensis ); strongly notched anterior zygosphenal margin; endozygantral foramen present (shared with Madtsoia madagascariensis , Powellophis and Gigantophis garstini ).

Autapomorphies: exceptionally large vertebrae [centrum length (cL): 37.5–62.7 mm and prezygapophyseal width (prW): 62.4–111.4 mm]; neural spine cross-section spade-shaped; poorly developed hemal keel which remains dorsal to the parapophyses; chisel-shaped posterior process of the hemal keel.

Description

The collection comprises 27 associated vertebrae which are mostly well-preserved and include a few in articulation (Figs.  2 A–T, 3 A–W). 22 out of the 27 specimens can be confidently assigned to the precloacal region based on the absence of hemapophyses, pleurapophyses and lymphapophyses, and are further constrained to a position anterior to the posterior trunk region as suggested by a greater mediolateral width of the neural arch compared to centrum length (sensu LaDuke 1 ; Rio and Mannion 2 ; Supplementary Tables 1 , 2 ; Supplementary Fig.  2 ). Such vertebral dimensions are usually found in large-bodied madtsoiids such as, Gigantophis 2 ; Yurlunggur 11 , Madtsoia 1 , 10 , 13 , and Wonambi 25 . Moreover, the closure of vertebral sutures suggests these specimens likely reached skeletal maturity, similar for instance to Madtsoia pisdurensis 8 .

Vasuki is characterized by exceptionally large vertebrae where centrum length (cL) and prezygapophyseal width (prW) range between 37.5–62.7 and 62.4–111.4 mm, respectively (Supplementary Table 2 ). We recognize this as an autapomorphy since these proportions eclipse all large-sized madtsoiids [ Madtsoia (cL = 18–25 mm; prW = 35–65 mm; LaDuke et al. 1 ), Gigantophis (cL = 28–41 mm; prW = 44–66 mm; Rio and Mannion 2 ), Platyspondylophis (cL = 18–21 mm; prW = 26–43 mm; Smith et al. 21 ) and Yurlunggur (cL = 15–22 mm; prW = 19–41 mm)]. Some caution, however, is warranted here because of uncertainties as to whether the largest size of these large-bodied madtsoiids has been captured, although, the same is true for Vasuki.

In overall form, the vertebrae of the new Indian taxon are massive (prW >> cL) and comprise a procoelous centrum. Anteriorly, the centrum preserves an anteroventrally inclined cotyle, whereas the posterior condyle is deflected posterodorsally resulting in considerable visibility of the condyle and cotyle in dorsal and ventral views, respectively (Fig.  2 C,E). In anterior view, the cotyle is strongly concave with its ventral margin recessed relative to the dorsal. The cotyle is mediolaterally wider than dorsoventrally high (Figs. 2 P, 3 A,F,K; IITR/VPL/SB 3102-4, coW/coH = 1.2; Supplementary Table 2 ) as in all madtsoiids [e.g., Gigantophis garstini 2 (NHMUK R8344, coW/coH = 1.2), Madtsoia madagascariensis (FMNH PR 2551, coW/coH = 1.24) Yurlunggur (NTM P8695-243, coW/coH = 1.22), and Wonambi (QMF23038, coW/coH = 1.4]. Laterally, the cotyle is bordered on each side by a well-developed and moderately deep paracotylar fossa (Figs. 2 K,P, 3 A,K). The dorsal and ventral margins of the fossa are prominent and defined by bony struts emanating from the dorsolateral and lateral cotylar margins, respectively. The lateral margin of the fossa, however, is flush with the surface. Furthermore, in some specimens the paracotylar fossa is divided into a shallower dorsal and deeper ventral sub-fossa by a weak secondary strut extending laterally from the dorsolateral margin of the cotyle. A tiny paracotylar foramen is present on the dorsal-most part of one or both paracotylar fossae, immediately lateral to the neural canal (Figs. 2 F,K,P, 3 A,K). While the presence of paracotylar fossae and foramina is a synapomorphy of Madtsoiidae 16 , 26 , the exact morphology of these features is variable across the clade. “ Gigantophis sp.” (CPAG-RANKT-V-1), Menarana nosymena and Adinophis fisaka (FMNH PR 2572) differ from Vasuki in the presence of paired paracotylar foramina on each side 1 , 16 , 27 . In Madtsoia and Eomadtsoia (MPEF-PV 2378) the foramina are deep and comparatively large, whereas in Yurlunggur these occur in clusters 7 , 8 , 10 , 11 , 13 . Eomadtsoia , however, shares with Vasuki the presence of prominent ventral rim of the paracotylar fossa 7 . In Gigantophis garstini the paracotylar fossa lacks a ventral margin and in Platyspondylophis the paracotylar foramen is absent altogether 2 , 21 .

The posterior condyle is transversely wider than high (IITR/VPL/SB 3102–4, cnW/cnH = 1.2; Supplementary Table 2 ) with the width progressively increasing from ATV (Fig.  2 B,G; cnW/cnH = 1.1) to MTV (Fig.  3 G, Q; cnW/cnH = 1.2–1.3). Similar proportions of the posterior condyle characterize most madtsoiids [e.g., Nidophis (LPB FGGUB v.547/3, ATV, cnW/cnH = 1.1; LPB FGGUB v.547/1, MTV, cnW/cnH = 1.2); Gigantophis garstini (NHMUK R8344, MTV, cnW/cnH = 1.2 Rio and Mannio 2 ); Madtsoia camposi (DGM 1310b, MTV, cnW/cnH = 1.3] (Fig.  3 G,I,Q). Furthermore, in posterior view, two small, distinct fossae are discernible on the lateral surface of the centrum immediately posterior to the left diapophysis (Fig.  3 G,I,Q). The fossae are vertically arranged, on top of each other, and separated by a prominent ridge. Whether these unilateral fossae represent an individual condition or a general feature cannot be currently ascertained and will require additional specimens of Vasuki .

The synapophysis is dorsoventrally high and comprises a distinct diapophysis and parapophysis (Figs.  2 M,R, 3 C,R) unlike in Gigantophis garstini , Madtsoia madagascariensis , and Madtsoia pisdurensis 1 , 2 , 8 . In anterior view, the orientation of the synapophysis changes from ventrolateral (Fig.  2 F,K) to somewhat laterally facing (Fig.  3 K,P,U) across the precloacal series. This change is marked by an increase in the synapophyseal angle (α), with the horizontal, from ATV (α = avg. 56.6°) to MTV (α = avg. 71.5°). A narrower synapophyseal angle was observed in most of the comparative madtsoiid taxa including Eomadtsoia [MPEF-PV 2378 (MTV), α = 45°], Gigantophis garstini [NHMUK R8344 (MTV) α = 48], Madtsoia madagascariensis [FMNH PR 2549 (ATV), α = 47°; FMNH PR 2551 (MTV), α = 56°], “ Gigantophis sp.” [CPAG-RANKT-V-1 (MTV), α = 56°], Madtsoia camposi [DGM 1310c (MTV), α = 57°], Wonambi [QMF23038 (MTV) α = 58°] and Madtsoia bai [AMNH 3155 (MTV), α = 62°]. In lateral view, the synapophysis is inclined at (β) 20°–27° from the vertical in Vasuki . This is similar to Wonambi [QMF23038, β = 25°], Nanowana [QMF19741, β =  ~ 25°], Madtsoia camposi [DGM 1310c, β = 26°] and Yurlunggur [P8695, β = 22°–26°]. In contrast, wider angles characterize Gigantophis garstini [NHMUK R8344, β = 30° 2 ], Platyspondylophis [β = 30°–35°], Madtsoia madagascariensis [FMNH PR 2549, β = 33°] and “ Gigantophis sp.” [CPAG-RANKT-V-1, β =  ~ 90°], whereas in Patagniophis [β = 7°–9°], Powellophis [PVL 4714–4, β = 18°] and Madtsoia pisdurensis [225/GSI/PAL/CR/10, β = 12°] the angles are narrower.

An arcuate paracotylar notch (sensu LaDuke et al. 1 ), between the ventral cotylar rim and the parapophysis, is consistently present in all specimens (Fig.  2 A,F). The parapophysis comprises a sub-rectangular facet, in lateral view, and extends below the ventral cotylar rim in ATV (Fig.  2 F,H,P,R). In MTV it lies dorsal to the ventral cotylar rim (Fig.  3 F,P) unlike Madtsoia pisdurensis and Gigantophis garstini where the parapophyseal base is ventral and in level with the ventral cotylar rim, respectively 2 , 8 . The diapophysis is bulbous and extends laterally beyond the prezygapophysis (Figs. 2 F,H, 3 P,R), contrary to Powellophis 3 , Patagoniophis australiensis 28 , Madtsoia pisdurensis 8 , Madtsoia madagascariensis 1 and Nidophis 9 . The dorsal margin of the diapophysis remains ventral to the dorsal cotylar margin in ATV (Fig.  2 A,F), but becomes level with the dorsoventral midpoint of the neural canal in MTV (Fig.  3 K,P). A similar disposition of the MTV diapophysis is observed in Madtsoia madagascariensis , Madtsoia camposi , Wonambi barriei and Adinophis 1 , 2 , 13 , 27 . The dorsal diapophyseal margin lies between the ventral margin of the neural canal and the dorsoventral midpoint of the cotyle in “ Gigantophis sp.” 16 , Gigantophis garstini 2 , Nidophis 9 , Yurlunggur 11 and Powellophis 3 . In Platyspondylophis the diapophysis extends beyond the ventral margin of the neural canal in all preserved precloacal vertebrae 21 .

The prezygapophyseal buttress is massive, lacks a prezygapophyseal process and bears an oblique, blunt ridge anteriorly (Fig.  2 F,K). In lateral view, the buttress is succeeded posteriorly by an elliptical fossa (Fig.  2 C,H,R). The fossa occurs immediately ventral to the interzygapophyseal ridge and medial to the diapophysis, similar to Madtsoia pisdurensis (Mohabey et al. 8 ). The prezygapophyseal facets are elliptical (5022–4, przL/przW = 1.3) and inclined ventromedially (prα = 20°–28°; Fig.  2 A,D,F,I). In dorsal view, these facets diverge at 45° from the sagittal plane, contrary to the transversely oriented facets in Madtsoia bai 10 , Madtsoia madagascariensis 1 , Platyspondylophis 21 , and Yurlunggur 11 . Strongly divergent prezygapophyses are also observed in Gigantophis garstini 2 (~ 70°) and Eomadtsoia 7 (60°–80°). The postzygapophyseal facets in Vasuki are also elliptical (IITR/VPL/SB 3102-8II, pozL/pozW = 1.2; Supplementary Table 2 ) and medioventrally oriented (poα = 12°–26°; Figs.  2 G,J, 3 B,E). The interzygapophyseal ridge is thick and posterodorsally directed, acting as a bridge between the pre- and postzygapophyses. A small lateral foramen is present ventral to the ridge (Fig.  3 L,Q) as in Powellophis 3 . In dorsal view the interzygapophyseal ridges are straight and differ from the arcuate ridges seen in most madtsoiids [e.g., Madtsoia , Gigantophis garstini , Wonambi , Yurlunggur and Platyspondylophis ] 2 , 8 , 10 , 11 , 13 , 18 , 21 , 28 .

The neural canal is reniform (Figs.  2 P,Q, 3 F,G) in cross-section and significantly wider than high (ncW/ncH = 3–3.6). It differs from the comparatively narrower and trilobate neural canal in Gigantophis garstini 2 (NHMUK R8344, ncW/ncH = 2.3), Platyspondylophis (WIF/A 2271, ncW/ncH = 2.1), Madtsoia (ncW/ncH = 1.3–2.3), Yurlunggur (NTM P8695-243, ncW/ncH = 2.3), “ Gigantophis sp.” (CPAG-RANKT-V-1, ncW/ncH = 1.8) and Powellophis (PVL 4714–4, ncW/ncH = 1.6), and the sub-elliptical canal in Wonambi (QMF23038, ncW/ncH = 1.3).

The zygosphene is trapezoidal and mediolaterally wider than high (zsW/zsH = 1.4–1.8; Fig.  2 A,K), as in Gigantophis garstini (NHMUK R8344, zsW/zsH = 2 2 ), Madtsoia bai (AMNH 3155, zsW/zsH = 1.8) and Madtsoia madagascariensis (FMNH PR 2551, zsW/zsH = 1.9). Transversely much wider zygosphenes characterize Nidophis (LPB FGGUB v.547/1, zsW/zsH = 5), Madtsoia camposi (DGM 1310a, zsW/zsH = 2.8), Eomadtsoia (MPEF-PV 2378, zsW/zsH = 2.6), Platyspondylophis (WIF/A 2269, zsW/zsH = 2.2) and Patagoniophis (QMF 19717, zsW/zsH = 5). In Vasuki , the zygosphene is wider than the cotyle, contrary to Gigantophis garstini , “ Gigantophis sp.”, Platyspondylophis and Madtsoia 1 , 8 , 10 , 13 , 16 , 21 . In anterior view, dorsal margin of the zygosphene is straight and the articular facets are steeply inclined (~ 40° form the vertical; Figs. 2 F,P, 3 A). These facets are oval in lateral view (IITR/VPL/SB 3102–6, zsfL/zsfW = 1.1). The anterior zygosphenal margin is markedly notched in dorsal view (zsα = 118°–128°; Figs. 2 I,N, 3 N), and differs from the non-notched zygosphene in Madtsoia pisdurensis 8 , Madtsoia camposi 13 , Eomadtsoia 7 and Platyspondylophis 21 . In “ Gigantophis sp.” (zsα = 145°) and Madtsoia madagascariensis (zsα = 145°–147°) the zygosphene is weakly notched.

The zygantrum is mediolaterally wider than high, with steeply inclined facets (50°–60° from the horizontal; Fig.  2 B,G,Q). The facets are elliptical in posterior view, but devoid of a median wall present in Gigantophis garstini 2 . An anteroventrally directed fossa is present at the base of each facet, and accommodates an endozygantral foramen (Figs. 2 G, 3 B). The latter is also present in Madtsoia madagascariensis 1 , Powellophis 3 and Gigantophis garstini 2 . In Vasuki , the zygantral roof above each facet is medio-dorsally convex and descends as sub-vertical ridges into the zygantrum (Fig.  2 Q) as in Madtsoia madagascariensis 1 . The roof is ventrally convex in Eomadtsoia and Madtsoia pisdurensis , and straight in Powellophis , Platyspondylophis , Yurlunggur and Gigantophis garstini 3 , 7 , 8 , 11 , 21 . A large, dorsolaterally oriented, elliptical parazygantral fossa flanks the zygantrum laterally on either side and bears a small parazygantral foramina (Fig.  2 B,G,Q).

The neural spine is dorsoventrally high (MTV, nsH/tvH = 0.21–0.29, Supplementary Table 2 ) and buttressed posteriorly by the neural arch laminae (Fig.  3 B–D,V,W). The latter extend anterodorsally from the dorsolateral margin of the postzygapophyses up to the dorsal spinal margin, resulting in a deep median embayment. In lateral view, the spine is steeply inclined posterodorsally (12°–19° from the vertical) with a concave anterior and a straight posterior margin. While a high neural spine characterizes most large madtsoiids [ Madtsoia camposi (DGM, 1310b, MTV, nsH/tvH = 0.22), Madtsoia madagascariensis (FMNH PR 2551, MTV, nsH/tvH = 0.33), Madtsoia bai (AMNH 3154, MTV, nsH/tvH = 0.22), Wonambi (QMF23038, MTV, nsH/tvH = 0.27)], it is more gently inclined in these large-sized taxa [e.g., Madtsoia madagascariensis (27°–33°), Wonambi (30°), Gigantophis garstini (30°)]. A convex anterior margin in Madtsoia madagascariensis as well as Powellophis and Nanowana further distinguishes them from Vasuki . Furthermore, the presence of a sharp postspinal lamina (sensu Tschopp 29 ) on the posterior spinal surface and a spade-shaped cross-section of the spine differentiates Vasuki from other madtsoiids (Figs.  2 D,S, 3 D). In dorsal view, the neural spine base is flanked on either side by a prominent fossa (Fig.  2 I,S), as in Madtsoia pisdurensis 8 and Madtsoia madagascariensis 1 . The fossae occur immediately posterior to the zygosphene and are bordered ventrally by weak, rounded bony struts emanating from the posterolateral zygosphenal margin. Ventral to these struts, a prominent foramen is present on the dorsal surface of the neural arch posterior to the zygosphene (Fig.  2 I), similar to Madtsoia madagascariensis 1 .

In ventral view, the centrum is triangular and widest across the parapophyses. Large paired subcentral fossae, more prominent in the anterior trunk vertebrae (ATV), occupy most of the ventral surface of the centrum (Figs.  2 J,O, 3 E,T). The fossae are bordered laterally by robust subcentral ridges that extend posteromedially from the parapophyses to the dorsoventral midpoint of the condyle. These ridges are straight to weakly convex in ventral view and differ from the concave ridges in Patagoniophis 28 and Madtsoia madagascariensis 1 . The subcentral fossae are separated by a transversely convex low hemal keel (Figs.  2 T, 3 E,O,T). The latter is broad, weakly raised and terminates anterior to the precondylar constriction. The hemal keel is not prominent, unlike the narrow/sharp keel in “ Gigantophis sp.”, Eomadtsoia , Nidophis , Nanowana and Powellophis 2 , 3 , 7 , 9 , 16 . In Vasuki , this keel remains dorsal to the ventral parapophyseal margin (Figs. 2 M,R, 3 M,R,V) unlike the hemal keel of other madtsoiids which descends below the parapophysis. Consequently, we identify the disposition of the hemal keel as an autapomorphy of Vasuki .

A small subcentral foramen is present on either side of the ventral shaft in Vasuki (Fig.  2 E,O,T), as in Madtsoia madagascariensis 1 , Madtsoia camposi 13 , Nidophis 9 , and Patagoniophis 28 . The hypapophysis is paddle-like with sharp lateral margins and extends up to the level of the ventral condylar rim in ATV (Fig.  2 G,H,J,L,M,O). The hypapophysis is directed posteroventrally unlike the ventrally directed hypapophysis in Madtsoia madagascariensis 1 and Patagoniophis 28 . Across the precloacals, the hypapophysis progressively reduces in prominence and is replaced by a chisel shaped structure with paired protuberances separated from the ventral condylar rim by a short, sharp ridge in the mid-trunk vertebrae (MTV; Fig.  3 J,O,T,X). This chisel shaped structure appears autapomorphic for Vasuki as it differs from the condition in other madtsoiids.

Phylogenetic analysis

The position of Vasuki within Madtsoiidae was tested in a modified version of the character-taxon matrix of Zaher et al. 30 (Analysis 1; see “ Methods ” section and Supplementary Note 2 ). 50 most parsimonious trees were recovered with a tree length of 1610, consistency index (CI) of 0.386 and retention index (RI) of 0.73. The resultant tree topologies are largely consistent with Zaher et al. 30 as Madtsoiidae was recovered as a distinct clade within crown Serpentes (Fig.  4 , Supplementary Fig.  3 ). Madtsoiidae, however, was poorly resolved and did not provide insights into the inter-relationship of Vasuki with the other members of the clade. The poor resolution is likely a reflection of the absence of cranial material in majority of madtsoiids and a function of the large matrix where very few vertebral characters could be scored for most madtsoiid taxa. We, therefore, ran a second analysis (Analysis 2) by removing all non-madtsoiid Serpentes and combining the cranial and vertebral characters of Zaher et al. 30 and Garberoglio et al. 3 , respectively (see “ Methods ” section and Supplementary Note 3 ). The latter dataset was used because as the study focused on madtsoiid ingroup relationships. Our analysis recovered only two most parsimonious trees with a tree length of 191, CI of 0.634 and RI of 0.62. Both trees (Fig.  5 , Supplementary Fig.  4 ) were mostly well resolved and the resultant topologies largely consistent with recent studies 2 , 3 , 7 on madtsoiid inter-relationships. Madtsoiidae shows size-based clustering with the small (< 2 m) and medium–large bodied (> 3 m) taxa recovered as separate clades (Fig.  5 ). Vasuki is nested within a distinct clade (Bremer support = 3) as a sister taxon to Indian Late Cretaceous Madtsoia pisdurensis  + North African Late Eocene Gigantophis garstini .

Phylogenetic position of Vasuki indicus gen. et sp. nov. IITR/VPL/SB 3102 in 50% majority-rule tree of Analysis 1. Clade comprising Vasuki indicus highlighted in pink. Numbers above and below nodes indicate the frequency a clade is represented in the most parsimonious trees and Bremer support values, respectively.

Phylogenetic position of Vasuki indicus gen. et sp. nov. IITR/VPL/SB 3102 in 50% majority-rule tree of Analysis 2. Clade comprising Vasuki indicus highlighted in pink. Numbers above and below nodes indicate the frequency a clade is represented in the most parsimonious trees and Bremer support values, respectively.

Estimation of body length

Quantitative estimates of total body length (TBL) of Vasuki were made based on two separate methods which have been used in recent years for size estimation of extinct large-bodied snakes (see “ Methods ” section and Supplementary Tables 3 – 5 ). In these methods TBL was regressed on the postzygapophyseal width (following Head et al. 31 ; Rio and Mannion 2 ) and the prezygapophyseal width (= trans-prezygapophyseal width; following McCartney et al. 32 , Garberoglio et al. 3 ), respectively. In the present study estimates were made from MTV (IITR/VPL/SB 3102-4, 3102-8I–II, 3102-11II–III), the largest specimens in the collection, following Rio and Mannion 2 , McCartney et al. 32 and Garberoglio et al. 3 . Both regression models were statistically significant (p < 0.05) and had a high explanatory power (r 2  = 0.83–0.96) which asserts their validity. The TBL estimates following Head et al. 31 ranges between 10.9 and 12.2 m (Fig.  6 A,B), whereas those following McCartney et al. 32 is between 14.5 and 15.2 m (Fig.  7 A). These estimates, however, should be treated with caution as the collection lacks posterior precloacal and cloacal vertebrae, and an understanding of the intracolumnar variation in madtsoiids is currently non-existent.

Regressions of vertebral metrics on total body length in extant boine taxa. Regression of postygapophyseal width on total body length in extant boine taxa from vertebrae 60% posteriorly along the vertebral column; p = 0.00000003, standard error =  ± 0.3 m ( a ). Regression of postygapophyseal width on total body length in extant boine taxa from vertebrae 65% posteriorly along the vertebral column; p = 0.00000001, standard error =  ± 0.2 m ( b ). Measurements of extant boine snakes taken from Head et al. 31 and plotted as black circles. Estimated body lengths of Vasuki indicus shown in red.

Regression of total body length on prezygapophyseal width in extant snakes. Measurements of extant snakes taken from McCartney et al. 32 and plotted as black circles. Estimated body lengths of Vasuki indicus shown in red. p = 0.000000000000003; standard error =  ± 0.09 m.

It is worth noting that the largest body-length estimates of Vasuki appear to exceed that of Titanoboa , even though the vertebral dimensions of the Indian taxon are slightly smaller than those of Titanoboa . We acknowledge that this observation may be a reflection of the different datasets used to formulate the predictive equations. However, we do not disregard the results based on the dataset of MacCartney et al. 32 , since the equations derived from the dataset of Head et al. 31 involve measurements of extant boine taxa that are taken from vertebrae 60–65% posteriorly along the column. Caution is warranted here because of the uncertainties surrounding the phylogenetic position of Madtsoiidae relative to crown snakes which make estimations based on a model depicting intracolumnar variation in vertebral morphology of a particular extant family/taxa tentative. Consequently, predictive regression equations following McCartney et al. 32 , which comprise vertebral data from an array of extant snakes, are also considered in our study.

Phylogenetic implications

The analyses presented here recovered a monophyletic Madtsoiidae with the clade placed within crown Serpentes in Analysis 1 (Fig.  4 , Supplementary Fig.  3 ). This is in accordance with most phylogenetic studies which assessed the relationship of snake total group within Squamata 30 , 33 , 34 , 35 . Furthermore, similar to Zaher et al. 30 , the tree topology in Analysis 1 recovered Sanajeh , Diniliysia , Najash stemward of crown Serpentes. Although the clade Madtsoiidae remains poorly resolved in Analysis 1, we found a combination of five synapomorphies supporting the placement of Vasuki within Madtsoiidae [centrum broad and subtriangular (ch 613); deep V-shaped embayment along posterior margin of neural arch (ch 614); presence of well-developed paracotylar foramina (ch 615); absence of prezygapophyseal accessory process (ch 616); presence of parazygantral foramina (ch 617)].

On the other hand, Analysis 2 gave insights into the ingroup relationships of Madtsoiidae (Fig.  5 , Supplementary Fig.  4 ). The resultant topologies are largely comparable with previous phylogenetic results 2 , 3 , 7 , 9 , as the taxa were found to resolve into two size-based clades (large vs small). While the possibility of size-related features driving such groupings cannot be ruled out, the recovery of small–medium sized taxa (e.g., Adinophis , Menarana , Powellophis ) within the large bodied clade suggests the presence of size-independent characters supporting these clades. A similar argument was also put forward by Garberoglio et al. 3 while discussing the occurrence of size-based clades within Madtsoiidae. However, none of the speciose genera (e.g., Madtsoia , Nanowana , Menarana ) included in this study formed monophyletic clades. The Bremer support for most internal nodes within Madtsoiidae remains low, although a few have comparatively higher support (Fig.  5 ). These results highlight the need for more rigorous sampling involving a better anatomical coverage of madtsoiids, leading to more robust phylogenetic relationships.

A unique combination of 7 synapomorphies nest Vasuki within Madtsoiidae [well-developed paracotylar foramina (ch 610); median prominence on ventral margin of centrum (ch 611); coW:dW between 0.5 and 0.3 (ch 634); lateral ridge on precloacal vertebrae below lateral foramen (ch 635); thick zygosphene (ch 645); moderately high neural spine (ch 648); lateral foramina present dorsal to subcentral ridges (ch 650)]. Furthermore, a combination of 6 unambiguous synapomorphies [posterior neural arch margin with deep V-shaped embayment (ch 614); oval precloacal cotyle (ch 615); transversely wide vertebrae (ch 629); hemal keel not sharp and narrow (ch 633); neural spine posteriorly canted (ch 652); presence of posterior process of hemal keel (ch 653)] support the placement of Vasuki with Gigantophis garstini and Madtsoia pisdurensis . Moreover, a single autapomorphy characterises Vasuki —chisel-shaped process of hemal keel (ch 654).

It is noteworthy that some of the synapomorphies mentioned above may be individually plesiomorphic characters, it is the unique combination of characters that justifies the recovery of Vasuki within Madtsoiidae. Previous studies (e.g., Head et al. 31 ; Mohabey et al. 8 ) have used character combinations to diagnose Madtsoiidae and other snake taxa.

Body length estimation and paleoecology

Our TBL estimations show that Vasuki was not only the largest madtsoiid (Table 1 ) but one of the largest snakes ever reported. Its vertebral dimensions are second only to the Paleocene Boinae Titanoboa (Head et al. 31 ). We attempted to infer the paleoecology of this large Indian madtsoiid from vertebral morphology since several previous studies on other extinct snakes (e.g., Palaeophis colossaeus , Powellophis and Madtsoia madagascarensis ) have highlighted the importance of vertebrae in paleoecological reconstructions 1 , 3 , 32 . The transversely wide vertebrae of Vasuki bear mainly laterally-directed synapophyses which would have been associated with laterally directed ribs, suggesting a broad and cylindrical body (see McCartney et al. 32 ). These features suggest a non-aquatic lifestyle for Vasuki as opposed to aquatic snakes which may possess high pterapophyses and have laterally compressed vertebrae with ventrally facing synapophyses, thereby placing the ribs beneath the vertebrae 3 , 32 , 36 . A high pterapophysis, however, is absent in many aquatic snakes and changes in the orientation of synapophyses from ventral to lateral across the vertebral column have been previously noted in aquatic snakes such as Simoliophis 37 . In hydrophiine sea snakes the vertebrae show true lateral compression only in the caudal region. Therefore, the possibility of an aquatic lifestyle for this giant Indian madtsoiid cannot be completely ruled out. An arboreal lifestyle is unlikely, judging from the large size of Vasuki and the fact that arboreal snakes tend to have elongated vertebrae with short zygapophyses 38 . A non-fossorial habitat is inferred here for Vasuki based on large body-size and non-depressed neural arch-spine complexes which would have placed the dorsal muscles (e.g., M. Semispinalis et spinalis, M. Interarticularis superior) away from the sagittal plane (sensu Auffenburg 39 ) 1 , 3 . This is further supported by the inferred presence of dorsoventrally thick M. multifidus , which originates from the anterodorsal neural spinal surface and inserts anteriorly onto the posterior margin of the neural arch laminae of the preceding vertebra. Gross similarity in vertebral morphology with extant large-bodied pythonids (e.g., Python and Malayopython ) 40 suggests a terrestrial/semi-aquatic paleohabitat for Vasuki . Corroborative evidence comes from the depositional environment of the Vasuki -yielding horizon, which was reconstructed as a back swamp marsh 23 , 41 , 42 , 43 , 44 , 45 , similar to the habitat of modern large pythonids.

Vasuki is envisaged as a slow-moving snake that possibly adopted a rectilinear locomotory mechanism as indicated by its large size, anteroposteriorly short and transversely wide vertebrae and absence of accessory prezygapophyseal processes 1 , 38 , 46 . A similar, anatomy-based inference was also drawn for the large Malagasy Madtsoia madagascariensis 1 , although rectilinear locomotion has also been documented in extant snakes with well-developed prezygapophyseal processes, such as vipers 47 . In spite of the uncertainties associated with the locomotory mechanism of Vasuki , it was perhaps too large to be an active forager and was more likely an ambush predator that would subdue its prey through constriction, similar to modern anacondas and large-bodied pythonids 1 , 42 , 48 .

The new Indian madtsoiid suggests a relatively warm climate (~ 28 °C) for the Middle Eocene (early Lutetian) paleogeographic position of India within the tropical zone 49 , 50 . This inference stems mainly from empirically derived dependence of poikilotherm body temperature on the ambient environmental temperature, which in turn controls the maximum body size 31 , 32 , 51 . Following Head et al. 31 , the mean annual paleotemperature (MAPT) for the Middle Eocene was estimated based on a relationship between the present mean annual temperature (MAT), TBL difference between Vasuki and reticulated python ( Malayopython reticulatus , the longest known extant snake) 42 and the mass-specific metabolic rate of pythons (see “ Methods ” section). The predicted MAPT falls between 27.2 and 28.6 °C, corresponding to the temperature range necessary for the survival of an 11–15 m snake, and suggests the Middle Eocene tropics were 0.7–2.1 °C (ΔT) warmer than at present (MAT = 26.5 °C 52 ). These estimates are largely comparable to those for the Palaeocene and Late Cretaceous based on the extinct Titanoboa (ΔT = 1.9–3.7 °C) and the frog Beelzebufo ampinga (ΔT = 2.1 °C), respectively 52 . Studies based on δ 18 O isotopic ratios from foraminifera and TEX86 index 53 , 54 , 55 , 56 have predicted high tropical sea surface temperatures (≥ 30 °C) during the Middle Eocene at ~ 47 Ma, whereas some estimates suggest tropical cooling for the early Middle and Late Eocene, but particularly during 45–34Ma 57 , 58 . The paleotemperature inferred here (< 30 °C) are lower than the afore-mentioned estimates (≥ 30 °C), but suggests that the Middle Eocene (early Lutetian, ~ 47 Ma) climate was warmer than at present.

A possible limitation of this study could be the use of a pythonid ( Malayopython reticulatus ) as the modern analog, especially since Pythonoidae and Madtsoiidae are phylogenetically distant. However, our choice of a modern analog is based on the inferred foraging mode and terrestrial/semi-aquatic paleohabitat of Vasuki , using anatomical data and the depositional environment of the fossiliferous horizon. The latter are similar to those of modern large pythonids which known to inhabit swamps, marshes and lowland forests 41 , 42 , 43 , 45 .

In India, Paleogene hyperthermal events, such as PETM and ETM2 are well documented from the Kutch and Cambay basins of western India based on δ 13 C negative excursions 23 , 59 , 60 , 61 . In comparison, studies on Paleogene paleotemperatures are scarce. Based on oxygen isotopic ratios, temperatures in excess of 30 °C were determined for the late Paleocene and early Eocene, whereas lower temperatures, ranging between 22 and 28 °C, were reported for the Middle–Late Eocene (~ 45–37 Ma) 62 , 63 . Our new estimates show that while the paleoclimate during the Middle Eocene (~ 47 Ma) became cooler compared to the Late Paleocene and early Eocene, it was still higher than at present. Further studies on Paleogene climates in the context of squamate speciation and extinction pattern are necessary in view of their suggested correlation with temperature patterns 64 , 65 , 66 .

Paleobiogeography

Madtsoiids were a major group of terrestrial snakes whose temporal range straddles the Cretaceous–Paleogene boundary. Fossil occurrences depict a skewed distribution of these snakes as most taxa are known from the Gondwanan landmasses, except Antarctica 1 , 2 (Figs.  8 , 9 ). The Laurasian record is extremely poor with madtsoiids known only from the Late Cretaceous (upper Campanian–Maastrichtian) of southern Europe 9 . The distributional pattern also shows the appearance of taxa on landmasses which were separated during the Late Cretaceous and Cenozoic but which share close phylogenetic relations indicating biogeographic links (sensu LaDuke et al. 1 ). This conundrum is aptly illustrated by the presence of Madtsoia in the Late Cretaceous (Maastrichtian) of Madagascar and India and the Early Paleogene of South America, and Menarana in the Maastrichtian of Madagascar and Spain 1 , 8 (Fig.  8 ). Previous studies put forward multiple scenarios for madtsoiid paleobiogeography including—a pan-Gondwanan distribution, albeit unsampled, during the Early Cretaceous followed by regional extinctions and/vicariance; presence of land bridges allowing dispersal between different Gondwanan landmasses and to Europe; sweepstakes dispersal between continents separated by oceanic barriers 1 , 8 , 9 . However, Rio and Mannion 2 argued in favour of an early pan-Gondwanan distribution and trans-Tethyan dispersals between Africa and Europe in the Late Cretaceous. The new Middle Eocene Indian madtsoiid further adds to the complexity of madtsoiid biogeography owing to its close phylogenetic ties with the Late Cretaceous Madtsoia pisdurensis from India and the Late Eocene North African Gigantophis garstini (Figs.  5 , 8 ).

Time-calibrated phylogenetic tree, based on the 50% majority-rule tree of Fig.  5 . Red star indicates position of Vasuki indicus . Clade for which biogeographic scenarios have been discussed are marked with colored nodes.

Palaeogeographic distribution of madtsoiids with taxa of different ages plotted together in a simplified Middle Eocene (50 Ma) map to show their global spatio-temporal occurences. Dashed-lines indicate possible dispersal routes between South America and Australia and the Indian subcontinent and North Africa. Palaeogeographic map after Scotese 43 and sourced from https://www.earthbyte.org/paleomap-paleoatlas-for-gplates/ [This work is licensed under the Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/ ]. Source of information on madtsoiid distribution from the Paleobiology database ( https://www.paleo-biodb.org/ ).

To assess the biogeographic significance of Vasuki we constructed a time-calibrated phylogenetic tree since this approach has been widely used in several previous studies for evaluating the paleobiogeographic significance of different vertebrate groups, including snakes and dinosaurs 2 , 67 , 68 , 69 . The rationale behind this approach is that phylogenetic relations are widely considered to be suggestive of biogeographic ties 1 , 70 , 71 , 72 . The phylogenetic tree used here is based on anatomically sparse data because most madtsoiid taxa are known exclusively from vertebrae and lack cranial material, resulting in weak support (Bremer support) for a majority of internal nodes within Madtsoiidae. For this reason, we restricted our biogeographic interpretations only to those nodes which had comparatively higher support (Bremer support ≥ 2; Fig.  8 ). Overall, the paleobiogeographic scenarios presented here should be treated with caution as future fossil discoveries may alter the phylogenetic position of some madtsoiid taxa and, in turn, the present biogeographic inferences.

Notwithstanding the above-mentioned limitations, the resultant tree in our study is consistent with the current consensus on madtsoiid origins as it suggests a Gondwanan origin reflecting the fact that all known early-diverging taxa are from erstwhile Gondwanan landmasses (Fig.  8 ). The tree topology argues for biotic exchanges between South America, Madagascar and Australia since the Malagasy Madtsoia madagascariensis (Late Cretaceous) and the South American Madtsoia bai (Eocene) are successive outgroups to the clade comprising the Neogene Yurlunggur and Wonambi from Australia. Paleogeographic reconstructions depict fragmentation of most major Gondwana landmasses by the early Cenomanian, with Indo-Madagascar separating from Australia–Antarctica by ~ 110 Ma 73 , 74 , 75 . However, previous studies suggested that land connections between South America and Australia facilitating faunal dispersal through Antarctica persisted till the early Eocene 1 , 75 (Fig.  9 ). On the other hand, the Malagasy–South American–Australian biotic link can likely be explained by the presence of madtsoiids or their most recent common ancestors in these continental blocks prior to their break-up. Recent studies on madtsoiid biogeography envisage an Early Cretaceous pan-Gondwana dispersal of these snakes, with ghost lineages from time-calibrated trees predicting an Aptian origin of Madtsoiidae 1 , 2 , 8 , 9 , 19 . The fossil record, however, is inconsistent with the hypothesized Early Cretaceous madtsoiid origins since their currently known earliest representatives are from the Coniacian–Santonian of Niger 1 , 2 , 9 , 76 , 77 . Future sampling from the pre-Maastrichtian horizons of Africa and Indo-Madagascar may help resolve this conundrum.

The Indian madtsoiids, namely Vasuki indicus , Madtsoia pisdurensis , and Platyspondylophis tadkeshwarensis , are resolved into two distinct sub-clades (Fig.  8 ). Platyspondylophis (Ypresian) and the Malagasy Adinophis fisaka (Maastrichtian) are recovered as sister-taxa, whereas Vasuki (early Lutetian) is the earliest-diverging member of a clade comprising Madtsoia pisdurensis (Maastrichtian) and the North African Gigantophis garstini (Priabonian). These phylogenetic relations suggest Late Cretaceous–Paleogene biotic exchanges between the Indian subcontinent, Madagascar and North Africa. Among the various competing hypotheses explaining such faunal links, Krause et al. 74 hypothesized connections ( stepping stones ) between the Indian subcontinent, Madagascar and Africa during the Late Cretaceous, which were possibly destroyed in subsequent tectonic events (e.g., subduction, hotspot related volcanism). The Oman-Kohistan-Ladakh arc (OKL) is another biogeographic pathway which is considered to have facilitated biotic interchanges between North Africa and India following the subcontinent’s collision with OKL at ~ 80 Ma 78 . While there is some support from paleomagnetic and radiometric data for the 80 Ma Indo–OKL collision 78 , subsequent studies based on detrital zircon ages and dating of post-collisional olasses have provided alternate explanations bearing on the sequence of accretion of the OKL with India/Asia 79 , 80 . These studies support OKL–Eurasia collision by ~ 100–80 Ma, with India colliding with Asia + OKL only during the Paleogene. This makes the possibility of Late Cretaceous Indo–African faunal exchange less likely 2 . More recent studies based on paleomagnetic data propose an initial collision between India and Kohistan-Ladakh arc at ~ 60–50 Ma followed by their final collision with Asia at ~ 45–50 Ma, with the arc being positioned at 8.3 ± 5.6°N at ~ 66–62 Ma 81 , 82 .

Among the scenarios discussed above we consider the following to be the most plausible explanation for the Indo-Madagascar-North African biotic links suggested by phylogenetic disposition of the Indian madtsoiids:

A sister taxa relationship between the Maastrichtian Malagasy Adinophis fisaka and Indian Platyspondylophis (Ypresian) suggests a dispersal event at or before Indo-Madagascar separation at ~ 88 Ma 83 . The direction of dispersal, however, remains uncertain as the available fossil evidence does not allow a critical evaluation of this hypothesis due to the poor sampling record of pre-Maastrichtian Malagasy and Indian deposits. However, recovery of Madtsoia from the Maastrichtian of both India and Madagascar 8 (Fig.  8 ) supports the prevalence of their biotic links, as also suggested by other groups including cordyliform lizards and the nigerophid Indophis 75 , 84 .

Post Indo-Madagascar separation at ~ 88 Ma, there was extended periods of isolation which ended with collision of the Indian subcontinent + Kohistan-Ladakh arc with Asia in the early Paleogene 50 , 81 , 82 resulting in biogeographic pathways with North Africa through southern Eurasia (Fig.  9 ).

Vasuki , Madtsoia pisdurensis and Gigantophis garstini form a distinct clade to the exclusion of others, with the earliest-diverging taxa from India (Fig.  8 ). This clade also shows close phylogenetic links between Late Cretaceous and Middle Eocene Indian taxa, suggesting a possible Indian origin for this clade. The placement of Gigantophis garstini within this clade indicates possible dispersal events from India to North Africa following India-Asia collision, consistent with the Late Eocene (Priabonian, 37–35 Ma 2 ) age of Gigantophis and recent paleobiogeographic reconstructions showing dispersal routes between India and North Africa via southern Eurasia following the collision 43 (Fig.  9 ). Whereas an African origin of Gigantophis garstini cannot be ruled out considering the recovery of madtsoiids from the Late Cretaceous deposits of that continent, the taxonomic and phylogenetic uncertainties offer little support for this hypothesis. However, Rio and Mannion’s 2 alternative explanation that an Early Cretaceous pan-Gondwanan dispersal and long ghost lineages may have led to close phylogenetic relations between Gigantophis garstini and the Indian madtsoiids, though potentially valid, is currently weakly supported because of poor sampling.

To summarize, we identify a lineage of exceptionally large-bodied madtsoiids (represented by the largest known madtsoiids, Vasuki and Gigantophis garstini ) which originated in the Indian subcontinent and subsequently spread to Africa via southern Eurasia during the Eocene. The discovery of Vasuki , and the sparse anatomical coverage of known madtsoiids highlight the need for rigorous sampling of Late Cretaceous and Paleogene Gondwanan deposits. Recovery of additional material and new taxa (including large-sized forms) may provide further insights into madtsoiid systematics and biogeography.

Osteological description

The osteological description of the skeletal specimens was carried out following the nomenclature of LaDuke et al. 1 , Rio and Mannion 2 and Mohabey et al. 8 . Different parameters of the fossil specimens were measured (Supplementary Fig.  2 ) using Mitutoyo digital callipers with a precision of 0.01 mm. Explanatory line drawings are used wherever necessary. The terminology for vertebral laminae and fossae follows Rio and Mannion 2 and Tschopp 29 .

The phylogenetic affinity of Vasuki was assessed in two separate analyses (Analysis 1 and 2). In Analysis 1 (Supplementary Dataset 1 ) the character-taxon matrix of Zaher et al. 30 was used. All non-Pan-Serpentes toxicoferans were removed except for Varanus exanthematicus which was used as the outgroup. 15 madtsoiid taxa, including Vasuki , were added. The character-taxon matrix included 72 taxa and 785 characters. The phylogenetic analysis was performed using TNT version 1.6 85 where the software memory was set to retain 10,000 trees and a display buffer of 10 Mb. The Traditional Search option was used to analyse the dataset. The constraints for the analysis included 50 replications of Wagner trees, in which the swapping algorithm was bisection reconnection with 10 trees saved per replication. To determine the robustness of the nodes, Bremer support values were calculated using the script bremer.run in which only trees suboptimal by 20 steps were retained.

In Analysis 2 (Supplementary Dataset 2 ) all non-madtsoiid Serpentes were removed except for the basal ophidians Najash and Sanajeh . The latter taxon was used as the outgroup. The dataset combined the cranial and vertebral characters of Zaher et al. 30 and Garberoglio et al. 3 , respectively. 3 additional madtsoiid taxa were included. The character-taxon matrix included 22 taxa and 656 characters. The analysis was performed using TNT version 1.6 85 following the software settings and search parameters of Analysis 1. The script bremer.run was used to calculate Bremer support values in which only trees suboptimal by 20 steps were retained.

Time-calibrated tree

This was constructed by plotting the temporal ranges of the snake taxa onto the majority rule tree of Analysis 2 against a numerically calibrated geological time-scale. The temporal ranges of the taxa used in this study have been obtained from the Paleobiology Database ( https://www.paleobiodb.org/ ), Rio and Mannion 2 , and Garberoglio et al. 3 .

Body length estimation

The body-length estimates of Vasuki were based on the datasets of Head et al. 31 and McCartney et al. 32 . The dataset of Head et al. 31 comprises measurements of trans-postzygapophyseal width (poW) and TBL of 21 extant boine taxa, whereas that of McCartney et al. 32 include measurements of trans-prezygapophyseal width and total body length of 21 extant snakes.

The following predictive regression equations were formulated after

Head et al. 31 :

where postzygapophyseal width (x) is equated with the total body length (y). The dataset was from vertebrae 60% posteriorly along the vertebral column, and was not log transformed as the measured parameters were approximately normally distributed (sensu Head et al. 31 ).

where postzygapophyseal width (x) is equated with the total body length (y). The dataset was from vertebrae 65% posteriorly along the vertebral column, and was not log transformed as the measured parameters were approximately normally distributed (sensu Head et al. 31 ).

McCartney et al. 32 and Garberoglio et al. 3 :

where trans-prezygapophyseal width (x) is equated with the total body length (y). Log transformed values of the measured parameters were used to normalize the dataset.

In previous studies, body lengths have been estimated for extinct snakes, which are part of extant clades, using maximum likelihood methods 31 , 32 . Head et al. 31 developed a model depicting intracolumnar variation of vertebral morphology in extant boines to assign vertebral specimens of the giant extinct boid Titanoboa to their most likely position in the vertebral column. Based on vertebral landmarks, the specimens of Titanoboa were matched to a position 60–65% posteriorly along the column (MTV, sensu Rio and Mannion 2 ), and size estimates were obtained by regressing TBL on poW based on vertebrae of extant boines from those positions. However, such models showing intracolumnar variation in madtsoiids are currently non-existent as very few of these snakes are known from complete/nearly complete vertebral column 2 . Size estimates of Vasuki were calculated in this study using MTV following Rio and Mannion 2 , although, these estimates should be considered tentative as the specimens of Vasuki cannot be assigned to the same position as the boine vertebrae used to formulate the equations. Also, there may be differences in the relationship between poW and TBL between extant boines and Vasuki . Furthermore, uncertainties associated with the phylogenetic position of Madtsoiidae relative to crown snakes, preclude formulation of models showing intracolumnar variation in vertebral morphology based on any extant clade. Consequently, predictive regression equations, based on data from an array of extant snakes from McCartney et al. 32 , were used to determine the body length of the new Indian taxon and therefore, the estimated lengths, though reasonable, should also be treated with caution.

Estimation of paleotemperature

Paleotemperature estimates were obtained using the following equation provided in Head et al. 31 :

where MAPT is the mean annual paleotemperature; MAT is the present mean annual temperature (26.5 °C 52 ); TBL M  = 10.05 m is the maximum total body length of Malayopython reticulatus 41 ; TBL V is the maximum estimated body length of Vasuki (15.2 m); Q 10 (mass specific metabolic rate of pythonids) = 2.6 86 ; α (metabolic scaling component) = 0.17 52 , 87 .

Since Madtsoiidae are an extinct clade, the body length of Malayopython reticulatus (Serpentes, Pythonidae) was used in the study as it is the longest known extant snake 42 . The choice of Malayopython as the modern analog is based on the similarity in gross vertebral morphology and, inferred mode of life and habitat between Vasuki and extant large-bodied pythonids 40 , 41 , 42 , 43 , 45 . However, in the absence of extant representatives of madtsoiids or their close relatives, the estimated paleotemperature values should be treated with caution.

Data availability

All data associated with the manuscript are provided in the Supplementary File.

Code availability

Nomenclatural acts. This published work and the nomenclatural acts it contains have been registered in Zoo- Bank, the proposed online registration system for the International Code of Zoological Nomenclature (ICZN). The LSIDs for this publication are urn:lsid:zoobank.org:act: 2F44E9BE-AE99-45E8-A132-D36A935D3B36 ( Vasuki ) and urn:lsid:zoobank.org:act: 0DD3FB9F-A500-4FFE-842C-EFE51EC76E4D ( V. indicus ).

Abbreviations

American Museum of Natural History, New York

Centre of Pure and Applied Geology, University of Sindh, Pakistan

Departamento Nacional de Produção Mineral, Rio de Janeiro, Brazil

The Field Museum, Chicago, USA

Vertebrate Paleontology Laboratory, Indian Institute of Technology Roorkee, Roorkee, India

Laboratory of Paleontology, Faculty of Geology and Geophysics, University of Bucharest, Bucharest, Romania

Vertebrate Paleontological collection, MuseoPaleontológico Egidio Feruglio, Trelew, Chubut Province, Argentina

Northern Territory Museum, Australia

The Natural History Museum, London, U.K.

Queensland Museum, Brisbane, Australia

Vertebrate Paleontological Collection of the Instituto Miguel Lillo, San Miguel de Tucumán, Argentina

Wadia Institute of Himalayan Geology, Dehradun, India

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Acknowledgements

The authors acknowledge with thanks the helpful comments, suggestions and a constructive critique of the manuscript by the reviewers and Editor, Scientific Reports. Authors also thank Ritu Sharma, Debasis Das, Vivesh Vir Kapur, N. Saravanan, Lisa Cooper, Lauren Stevens and Hans Thewissen for help during field work and, Aatreyee Saha, Abhay Rautela and Poonam Verma for help and discussions. The Science and Engineering Research Board (SERB) (Grant no. PDF/2021/00468 as National Post-doctoral Fellowship to DD) and the Department of Science and Technology (Project no. SR/S4/ES-222/2006 to SB), Government of India are acknowledged for financial support. DD would like to acknowledge IIT Roorkee for providing infrastructural facilities. SB would like to acknowledge support obtained from IIT Roorkee as part of his Institute Chair Professorship.

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S.B. and D.D. conceived the problem. S.B. collected the fossils. D.D. and S.B. analysed and interpreted the data and wrote the manuscript. S.B. and D.D. were involved in further revisions.

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Datta, D., Bajpai, S. Largest known madtsoiid snake from warm Eocene period of India suggests intercontinental Gondwana dispersal. Sci Rep 14 , 8054 (2024). https://doi.org/10.1038/s41598-024-58377-0

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DOI : https://doi.org/10.1038/s41598-024-58377-0

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