All reviews of published articles are made public. This includes manuscript files, peer review comments, author rebuttals and revised materials. Note: This was optional for articles submitted before 13 February 2023.
Peer reviewers are encouraged (but not required) to provide their names to the authors when submitting their peer review. If they agree to provide their name, then their personal profile page will reflect a public acknowledgment that they performed a review (even if the article is rejected). If the article is accepted, then reviewers who provided their name will be associated with the article itself.
Thank for addressing these final suggestions which include rephrasing/reformatting some aspects, adding the impact of musculature in the tail of Tyrannosaurus, and adding a DOI for the GitHub materials. I look forward to seeing this published.
[# PeerJ Staff Note - this decision was reviewed and approved by Nigel Andrew, a PeerJ Section Editor covering this Section #]
This is the review of the revised version. The author has addressed my single concern about the lack of musculature on the tail of the Tyrannosaurus that was originally supplied. The tail is now anatomically correct and the results coming from the analysis are consistent with previous findings.
The experimental design is all fine and meets PeerJ requirements.
The results appear valid given the methods and data used.
I have no further criticisms or suggestions to make with the manuscript.
The revised manuscript and additional examples make your analyses and comparisons easier to follow and of broader relevance. I would like to see this work published, but some minor but crucial points remain to be addressed:
1) You mention in the abstract and introduction that body mass and surface area is impossible to obtain in all extinct species. This is not entirely true – likely in most vertebrates but surface area can be calculated for extinct animal species with closed shells through CT (e.g., brachiopods, bivalves). Please rephrase.
2) Tyrannosaurus tail reconstruction: As highlighted by reviewer 2, the cross-sections of the tail completely neglect the presence of the substantial leg retractor muscle which leads to an underestimation of the tail mass and a more anteriorly located CM when compared to other studies (see suggestion provided by reviewer 2). Please use this suggestion or at least explicitly discuss this issue.
3) Add DOI to supporting materials on GitHub repository: As links on GitHub could change, please make sure an archive of your tutorial/supporting data on GitHub with digital object identifier is made and the DOI explicitly mentioned in the manuscript. This is crucial to be able to reproduce your study on the long-term. This can be done through Zenodo as far as I am aware: https://docs.github.com/en/repositories/archiving-a-github-repository/referencing-and-citing-content
4) Formatting: there are some additional formatting or typographical/language issues (compare suggestions of reviewer 2)
Please make sure to address these as well as all other points including those raised in annotated pdfs. I look forward to receiving the revised manuscript.
I am satisfied that the revised manuscript has adequately addressed my concerns from the original submission. I am happy to support acceptance of this revision.
I am satisfied that the revised manuscript has adequately addressed my concerns from the original submission. I am happy to support acceptance of this revision.
I am satisfied that the revised manuscript has adequately addressed my concerns from the original submission. I am happy to support acceptance of this revision.
This revised version of the original submission has responded to all of my previous comments, questions and suggestions.
The writing is clear and my requests for the addition of the definite article 'the' in many places in the text have been met.
The requested clarifications of the figures have also been done as requested.
The literature citations are all fine and bit more comprehensive than before.
The experimental design meets all the PeerJ requirements listed.
The results are consistent with the proposed methods and the 3D models provided as a test cases. All the PeerJ conditions for valid results and conclusions are met.
I only have one significant correction to make:
The cross-sections of the tail of Tyrannosaurus presented in Figure 6 completely neglect the presence of the substantial leg retractor muscle that lies along the proximo-ventral two-thirds of the tail - the caudifemoralis longus. This muscle is present in all limbed diapsids (eg. lizards, crocodilians, non-avian dinosaurs) Neglect of this muscle in the model results in an underestimation of the tail mass and a more anteriorly located CM when compared to other studies. See the attached JPEG image of what the base of the tail should look like with the proper musculature.
There are also a handful of wording corrections to make as well. I have indicated this in the annotated review PDF which is attached.
You provide a new way to estimate body volumes and surface areas from cross-sections and test its performance. This approach is of interest for the community but there are crucial points which need to be addressed before publication. I apologize for the delay in getting my decision to you, but I was hoping to receive an additional review which got an extension but unfortunately did not arrive. However, I feel that the input of the reviewers and my own should be sufficient to revise the manuscript. The main points to be addressed are:
Background on competing approaches: I agree with reviewer 1 that more information and comparisons on the competing approaches needs to be provided for the readers not so familiar with these approaches in the introduction and discussion. See also the recommendations of reviewer 2 concerning particularly prior surface area estimations.
Validity of findings: Your test seem to produce valid results and comparisons seems adequate at first glance (compare reviewer 2) but the reasons for their performance are not fully explored. As pointed out by reviewer 1, the test of the methods lack generality and have inconsistencies. Please repeat test 1 by using more specimens, and using entire specimens as suggested by reviewer 1. Comparisons between methods have inconsistencies as more slabs are used in CS than other methods making it difficult to assess if it is truly a better methods or because specimens were able to be measured with more precision (compare reviewer 1).
Scientific reproducibility and accessibility: The new cross-sectional method is described in sufficient details to enable replication pending considerable effort.
You present a new method, but the software does not appear to be publicly available and no clear guidelines or limitations for its use are provided (compare reviewer 2). This makes it hard to reproduce your approach and widely apply it for other taxa in a straightforward way (compare reviewer 2). Particularly critical is the complexity of generating initial 3D models in an expensive and advanced software not accessible to all (e.g., Rhino; compare reviewer 2). Reviewer 2 also points out that Rhino already generate volumes and surface areas, which makes your approach a bit redundant unless you can make the entire process available in a publicly available software (e.g., Motani 2023 - which method you analyzed - makes his software available for use). As pointed out by reviewer 2 your approach could be easily extended by computing the centroid of the used 3D shapes or entire body region to locate the balance points or center of pressure for life calculations. The limitation of your approach that it depends on the body or body part being straight and how (if at all) it can be extended to cope with curved necks should be highlighted and discussed (compare reviewer 2).
Formatting and language issues: once revised, please check your manuscript for any inconsistencies (see suggestions by reviewers 1 and 2).
Figures: Please follow the recommendations of reviewer 2 to rework the dashed diagonals representing the diameters on Figure 2 and show the representative frustum and its subsection with same orientation as the body forms shown in figures 1 and 3. Please also follow the recommendation of reviewer 2 to present several sets of cross-sections from the full axial bodies and limbs from a limited selection of the models shown in figure 3 and to include in samples one each of a toothed and baleen cetacean, an ichthyosaur, a plesiosaur, the sturgeon and the turtle.
Please address these points as well as all other points raised including those in annotated pdfs.
I look forward to receiving the revised manuscript.
Generally well written but would benefit from editorial assistance with a fluent English writer to clean up numerous typos, grammatical errors, and occasionally non-standard sentences. Background information on the two competing methods (GDI and Paleomass) is insufficient at introducing them to readers, with critical information placed instead in the Conclusions.
The overall design is fine. However, see below for concerns on the validity of the findings, which bear on the design.
Test 1 (how many slabs to cut the digital specimen into?) is lacking in generality; it should be repeated using more specimens, and using entire specimens. Tests 2 and 3 (how does CS compare to alternative methods?) appear to have inconsistencies in how many slabs were used. The CS method appears to, in practice, use 10-times more slabs than the other methods, making it unclear whether the improved performance of the CS method is due to it being a better method, or because the specimens were able to be measured with more precision (because of using more slabs).
See attached.
The use of English is almost fine. I have revised some of the word usage and phrases. In many places the definite article ‘the’ is needed.
The introduction and background information are almost fine. The introduction does a good job of reviewing previous mass estimation methods, but fails on prior surface area estimations. This is unfortunate as the new method proposed in the paper does make and test surface area estimates. Two examples of the applications of animal surface area estimates to cite can be found in these two papers:
Henderson, D. M. (2013). "Sauropod necks: were they really for heat loss?" PLoS ONE 8(10): 1-8.
Sereno, P. C., et al. (2022). "Spinosaurus is not an aquatic dinosaur." eLife 2022: 1-15. (Figure 5)
The figures are almost fine. The dashed diagonals representing the diameters on figure 2 are confusing and took me a few seconds to realize what they were trying to show, and should be drawn differently. Also, the representative frustum and its subsection should be shown with same orientation as the body forms shown in figures 1 and 3.
Several sets of cross-sections from the full axial bodies and limbs from a limited selection of the models shown in figure 3 should be presented. The samples should include one each of a toothed and baleen cetacean, an ichthyosaur, a plesiosaur, the sturgeon and the turtle.
The research is appropriate for PeerJ. As the author states in the text, knowing the body masses for animals provides a foundation for other studies. The new cross-sectional method is described in sufficient detail to enable replication, and does produce valid results, and the testing and comparison of this new method appears to be adequate.
The results are reasonable. The conclusions are supported by the presented data.
At first glance the method does seem simpler and more direct than others, but the complexity of generating the initial 3D models in an expensive and complicated bit of software such as Rhino (used for the sources of the contours), and extracting the section contours is glossed over. It appears that the Rhino software used to produce the models already generates volumes and surface areas, so the new method seems a bit redundant.
The author has missed an opportunity to compute the centroid of the 3D shapes being analyzed. By adding an extra ‘l’ term in the integrand at the bottom of page 4, the centroid, , for the kth body segment could be determined with the following expression:
SEE ATTACHED PDF FOR THE EQUATION THAT DIDN'T TRANSFER TO THE WEB PAGE
This could be extended to determine the centroid for an entire body region. The centroid is useful to locating the balance point (if a density distribution is developed) or the centre of pressure for lift calculations (eg.for the underwater flying manta ray).
One serious limitation of the method is that it appears to depend on the body or body part being straight. Curved structures such as necks or tails would confound the simple, linear scaling scaling used. I would like to see if this new method could cope with the curved neck of a sauropod. See that attached image of a sauropod that could be used to test this. This image is from Henderson (2013) cited above.
The author presents his method, but it is up to the motivated reader to implement it. Most of the biologists and palaeontologists that I know who could use it could not even begin to develop the software to implement the method. Motani (2023), the author whose method is analyzed by the present author, does make his software available for use.
All text and materials provided via this peer-review history page are made available under a Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.