Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia

Anthony J. Martin; Melissa Lowery; Michael Hall; Patricia Vickers-Rich; Thomas H. Rich; Claudia I. Serrano-Brañas; Peter Swinkels

doi:10.1371/journal.pone.0293308

Peer Review History

Original SubmissionMay 27, 2023
30 Aug 2023 Decision Letter - Miquel Vall-llosera Camps, Editor PONE-D-23-16348Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, AustraliaPLOS ONE Dear Dr. Martin, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. I would like to sincerely apologise for the delay you have incurred with your submission. It has been exceptionally difficult to secure reviewers to evaluate your study. We have now received two completed reviews; the comments are available below. The reviewers have raised some scientific concerns about the study that need to be addressed in a revision. 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Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: I have very little to comment on regarding the actual text of the paper, so I will submit my comments here. The manuscript details a novel avian ichnofauna from Early Cretaceous Gondwana. In short, this is a tremendous find, and provides important information on the paleodiversity of early avians. Given the challenging nature of the present-day environment and the nature of the preservation, the authors approached the description of these tracks with an appropriate level of caution: suggestions of possible ichnotaxonomic assignments were made without formal designation. This provides the opportunity for more detailed examination of the tracks and the possibility for future surveys of the Footprint Flats and Honey Bay localities for more specimens. Detailed measurements and data tables were provided, which will be very useful for future analyses, and the images in the paper and the supplemental information were clear and without overinterpretation. I agree with the authors that photogrammetric images are not required at this stage. Also, the encrusting tidal fauna on many of the tracks would provide a great deal of artificial relief to a heat map. The only item that I would like to see expanded on may be the possible migratory potential for volant Early Cretaceous avians to polar regions during the spring and summer as we see in many of our modern analogs. Would a north-south migration of Barremian – Aptian shore and wading birds during the breeding season have any geographic barriers? I recommend that PLOS One accept this paper for publication. Reviewer #2: A competent paper with broad coverage of avian tracks literature I am a little surprised to see the Wonthaggi tracks compared with such a wide variety of ichnogenera. it would be nice to narrow it down a bit if possible. For example, tracks are much larger the Geongsangornipes and lack web traces. RE morphometric tables it would be nice to place a line with mean measurements at bottom of each table Please refer to digit traces not "actual" digits when appropriate ****** 6. 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Revision 1
21 Sep 2023 Author Response The uploaded response letter contains all of our responses to the reviewer and editor comments. However, if that information needs repeating here, it is copied and pasted below. ********************** Dear Dr. Miquel Vall-llosera Camps, Thank you very much for the helpful reviews of our research article, Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia (PONE-D-23-16348), which we originally submitted to PLoS One on May 27, 2023. My coauthors and I are satisfied that the reviews were both thorough and fair, and in this letter, we address any concerns or suggestions provided by the two external reviewers. Reviewer #1 (Reviewer concerns and suggestions in italics, our replies in bold.) I have very little to comment on regarding the actual text of the paper, so I will submit my comments here. The manuscript details a novel avian ichnofauna from Early Cretaceous Gondwana. In short, this is a tremendous find, and provides important information on the paleodiversity of early avians. Given the challenging nature of the present-day environment and the nature of the preservation, the authors approached the description of these tracks with an appropriate level of caution: suggestions of possible ichnotaxonomic assignments were made without formal designation. This provides the opportunity for more detailed examination of the tracks and the possibility for future surveys of the Footprint Flats and Honey Bay localities for more specimens. We appreciate Reviewer #1’s affirmation of the paleontological importance of these trace fossils, which we hope will expand our understanding of Early Cretaceous avian biodiversity and paleobiogeography. We also agree that our study represents an opportunity for further study of these tracks, while encouraging further field work aimed at discovering and documenting more specimens in coastal exposures of the Wonthaggi Formation near Inverloch, Victoria. Detailed measurements and data tables were provided, which will be very useful for future analyses, and the images in the paper and the supplemental information were clear and without overinterpretation. I agree with the authors that photogrammetric images are not required at this stage. Also, the encrusting tidal fauna on many of the tracks would provide a great deal of artificial relief to a heat map. We agree with the reviewer that our descriptions and interpretations should contain enough evidence for future workers interested in re-studying these Early Cretaceous bird tracks, and that our methods for studying the tracks were appropriate given their modern environmental setting and preservational conditions. The only item that I would like to see expanded on may be the possible migratory potential for volant Early Cretaceous avians to polar regions during the spring and summer as we see in many of our modern analogs. Would a north-south migration of Barremian–Aptian shore and wading birds during the breeding season have any geographic barriers? We thank the reviewer for suggesting that we link our reported avian footprints with the migratory potential of Barremian-Aptian flighted birds. As a result, we have added the following paragraph on that topic in the manuscript, as well as two new references cited in that paragraph. The wider implications of a diverse Early Cretaceous avifauna in circumpolar Australia, and flighted birds in particular, may also provide an early glimpse of seasonally linked migrations in birds. In this scenario, Early Cretaceous birds might have flown to Australia from nearby northern regions of Gondwana during Southern Hemisphere springs, then returned to those places during Australia-Antarctica winters. In contrast, paleogeographic maps indicate lengthy oceanic distances between Asia and circumpolar Australia during the Barremian-Aptian [95], which argue against birds having direct north-south migration routes between Laurasia and Gondwana. Nevertheless, the morphological similarity of some Wonthaggi Formation bird tracks to those reported from eastern Asia [90-92] may also reflect the dispersal of Early Cretaceous flighted birds from Laurasia into other parts of Gondwana before they arrived in Australia. Current assessments of how winged migrations evolved in birds are based on modern range maps and climatic niches viewed through phylogenetic trees [96], but do not include trace-fossil data. In this respect, then, avian trace fossils in polar environments of Early Cretaceous Australia provide important insights on the global paleobiogeography and adaptations of birds relatively early in their evolutionary history. References: 95. Scotese CR. Atlas of Early Cretaceous Paleogeographic Maps 2014; PALEOMAP Atlas for ArcGIS, 2, The Cretaceous, Maps 23-31, Mollweide Projection, PALEOMAP Project, Evanston, IL. 96. Dufour P, Descamps S, Chantepie S, Renaud, J, Guéguen M, Schiffers K, Thuiller W, Lavergne S. Reconstructing the geographic and climatic origins of long-distance bird migrations. Journal of Biogeography 2020;47: 155-166. Reviewer #2 (Reviewer concerns and suggestions in italics, our replies in bold.) Reviewer #2: A competent paper with broad coverage of avian tracks literature I am a little surprised to see the Wonthaggi tracks compared with such a wide variety of ichnogenera. it would be nice to narrow it down a bit if possible. For example, tracks are much larger the Geongsangornipes and lack web traces. We justify our comparison of the Wonthaggi Formation tracks to a wide variety of ichnogenera from elsewhere because these tracks represent the oldest documented avian tracks in Australia and the remainder of the Southern Hemisphere. Moreover, the tracks reflect a previously unknown diversity of track forms and sizes from Early Cretaceous strata of those places. Thus our comprehensive coverage of avian-affiliated ichnogenera was intended to benefit researchers who can then more easily compare ichnogenera from widely separated places, such as those from eastern Asia and North America. We also meant to provide future researchers with a checklist of avian ichnogenera (e.g., Table 2) that might prove useful when documenting future discoveries of other Cretaceous avian footprints, whether in Australia or elsewhere. In short, we advocate for erring on the side of comparing “too many” avian-affiliated ichnogenera rather than “too few,” and do not feel a need to narrow down the list of ichnogenera in our report. RE morphometric tables it would be nice to place a line with mean measurements at bottom of each table. This is a good suggestion, as it will aid readers when comparing overall statistics (Table 1D) to those of anisodactyl incumbent and anisodactyl tracks (Table 1A and 1B, respectively). As a result, we added mean and standard deviation at the bottom of each of the first two parts of Table 1. However, we did not add these values for Table 1C, which only had measurements for two tracks and included extrapolated widths and length:width ratios. Please refer to digit traces not "actual" digits when appropriate. We included most of Reviewer #2’s suggested editorial changes in the manuscript, such as adding “trace” or “traces of” to “digit” and other anatomical terms related to foot morphology of the tracks. However, we did not change “active marine platform” to the reviewer’s preferred “marine platform setting” or “wave-cut platform setting,” which we felt unnecessarily complicated its description. Similarly, we meant to use “sketches” rather than “tracings” (p. 16) when describing our initial field assessments of the tracks, so this is unchanged. Associate Editor (editor concerns and suggestions in italics, our replies in bold) The resubmitted manuscript differs from the original in the following respects: - Added a paragraph suggested by Reviewer #1 on possible connections between Early Cretaceous bird tracks in a circumpolar region of Gondwana and winged migrations. - Added two references cited in that paragraph to the bibliography. - Made most of the minor editorial corrections in the manuscript suggested by Reviewer #2. - Made further minor editorial corrections to the final manuscript by one of us (AJM) after proofreading (shown in the tracked changes). - Added to the Acknowledgements, with three of us (PVR, AJM, MH) contributing to that. - Added a list of tracks in this study that were molded and cast in Supporting Information 2. - Uploaded, corrected, and saved all figures using the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool. We also note that Figure 1B, which is a satellite image of the field area, was downloaded from U.S.G.S. Earth Explorer site (https://earthexplorer.usgs.gov), which is among the approved public-domain sources listed by PLoS One for Creative Commons (CC BY 4.0). However, if this figure requires further sourcing or replacing, we would appreciate specific directions on how to comply. As for competing interests, the authors again declare that no competing interests exist. Thank you again for your consideration of our manuscript, and please let us know if you require anything more from us to satisfy the publication requirements of PLoS One. Sincerely, Anthony J. Martin Department of Environmental Sciences Emory University Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0293308.r002
10 Oct 2023 Decision Letter - Jun Liu, Editor Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia PONE-D-23-16348R1 Dear Dr. Martin, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Jun Liu Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0293308.r003
Formally Accepted
23 Oct 2023 Acceptance Letter - Jun Liu, Editor PONE-D-23-16348R1 Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia Dear Dr. Martin: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Jun Liu Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0293308.r004

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