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Dear authors,
Thank you for your revised manuscript, and the detailed changes you made in response to the reviewers' comments. I am happy to accept it for publication.
The production team will contact you to take you through the proofing stages.
Congratulations, and I hope you will continue to use PeerJ as your publication venue in the future.
[# PeerJ Staff Note - this decision was reviewed and approved by Kenneth De Baets, a PeerJ Section Editor covering this Section #]
Dear authors,
The reviewers have not come to a common decision, but I have accepted the ‘minor revisions’ recommendation of reviewer two.
Both reviewers are very complimentary about your response to their initial review. Thank you for so positively answering their review comments. While you and reviewer two have disagreements; you both have constructively engaged with the review process and I believe have a common understanding of each other’s opinions.
I look forward to receiving your revised manuscript.
In general, I found this version of the manuscript to be much improved win basic reporting. There are still some minor clarity issues and one reference that images multiple generation of Haversian canals that I pointed out in my marked version of the manuscript. I still find some of the descriptions and figures disjointed in describing the histology. I've made a few comments in the manuscript, but I would recommendation the authors take the time to make sure that each claim made in the description is highlighted in the image either by clearly imaging the feature or labeling it.
I believe the layout of the author's argument is much improved from the original version I reviewed. I still have major reservations about the similarities of periosteal bone in cranial and appendicular elements as these elements tend to have different growth rates and therefore likely different histological features. However, as my hunch and the authors' hunch on cranial vs. appendicular periosteum remains a largely untested notion, I appreciate the authors' response to this concern and don't see this as a major experimental design flaw.
In rereading the manuscript, I realized that how porosity (entire cross-section vs. subsampling) methods should be described a bit more. I've left comments in the marked version of the manuscript attached to this review.
I appreciate the authors' in-depth response to my previous concerns regarding the validity of the findings and find their extensive edits do help present a more measured conclusion that more accurately reflects the nature of the data.
Meets editorial standards in all aspects
Meets editorial standards in all aspects
Meets editorial standards in all aspects
The authors have alleviated all my concerns regarding the first version of this manuscript. The figures are clear and illustrate what they mean, the text is self-contained and the descriptions of the histology are clear and adequate, as is the description of their new terminology.
Dear authors,
Based on the reviewer comments, I have made a decision of 'major revisions'.
As you are no doubt aware, I am not the original handling editor. He is unfortunately not available at present, and I have been asked to 'step in'. The original decision was 'reject' (which I as section editor approved). You appealed the decision, and we asked one of the reviewers if they had the chance to review your Supplementary files. An updated review has thus been submitted by R2.
I would like to take this opportunity to apologise, as I did not notice the issue you raised when I made my section editor approval.
Reviewers 2 and 3 have major issues that will need to be addressed prior to resubmission. Please note, we do not require authors to agree with reviewer comments. But if you do disagree, you need to provide a thorough rationale as to why you disagree. But please pay special attention to the comments of reviewer 2, as they will need to be addressed.
I look forward to receiving your revised manuscript.
I am Marcello Perillo, and recently I submitted a manuscript for publication to PeerJ.
Sadly the manuscript got rejected after reviews, as it appeared to me mainly in light of one of the reviewer comments (reviewer number 2).
I need to state first that it is far from my intent to judge the review work of reviewer number 2, which was most kind in allowing us to have a contact reference.
Nor is my intention to reject peer review and I am grateful for the comments on our work (many of the suggestions from the reviewers have already been implemented in our manuscript).
It is my first time going through the publishing process, and being inexperienced, I would like to ask
1) if there is the possibility of reconsidering this decision
2) how to proceed if possible.
- Reviewer number 2 presented doubts on our conclusions and I believe that by contacting her directly, we could either convince her of our positions (I do have a list of answers on the comment she provided), or gain new critical data for the study.
3) Would contacting the reviewer directly be allowed?
4) Would proving our point to the reviewer change the state of the rejection?
Of much urgency to me is to point out that some of the comments left by the reviewer number 2 suggest that the supplementary material provided was not observed (she required twice photos of the specimens that were provided in the supplementary).
It is of most importance because this would have answered four of the critical statements that lead the reviewer to express major concerns regarding the data presented.
Reviewer number three suggested that the material placed in supplementary should have been included in the main text. Therefore, I believe that, had we made the supplementary material directly available on the text, also reviewer number 2 may have suggested major revisions instead of the complete rejection of the publication.
The switch of this informative material to supplementary was done for economy of text space.
In view of the serious flaws in experimental design identified by Reviewer 2, I cannot accept your manuscript for publication. I am sorry that I cannot be more positive on this occasion.
[# PeerJ Staff Note - this decision was reviewed and approved by Mark Young, a PeerJ Section Editor covering this Section #]
please see my comments in the attached pdf
in addition please delete repetitions from the text and check gramma and language, in some places the wording/sentences are strange, difficult to understand.
no comment
no comment
no comment'
See below
See below
See below
[PeerJ Staff Note: The text below is an amended review from Reviewer 2, it replaces and overwrites the prior review text]
The authors present histological data on specimens whose taxonomic affinity has been a mystery for some time. These specimens have been assigned to a range of fossil vertebrates, and the authors present histological data that they report to support an ichthyosaur designation. I have to deeply apologize for missing the supplementary material during my first review of this article. That is my mistake and the supplementary material did address some of my initial concerns. That said, after having reviewed again with the supplementary material, I still have major reservations about this study. I believe this work can be publishable, but not in it’s current format and with a reframing of the data presented and conclusions. I will reiterate the following concerns I have about the hypothesis testing of this project:
-Bone histology is not uniform across elements. And this is particularly true when comparing cranial and appendicular elements. This is even more important when using histology to make inferences about taxonomy. The jaw and the appendicular skeleton differ in growth rate, development, and biomechanics and therefore cannot reliably be used in comparisons for taxonomic assignment. The specimens that have a previously established giant ichthyosaur taxonomic designation come from the lower jaw. This creates concern for me on two fronts: 1) the unknown giant bones are ruled out as belonging to another large reptile based on not meeting a combination of previously described features in those groups. This logic is based on comparisons that are largely made from other groups’ appendicular elements (especially dinosaurs) and therefore is not a true test of diagnostic features. 2) As far as I can tell, the unknown bones do not contain enough morphology to rule out them being appendicular bones (and in fact the authors refer to them as even potentially being long bones). Therefore, the use of suranglular bones from known specimens (e.g. RTMP-1994-378-0002) cannot be a strict comparison for unidentifiable fragments. If those fragments are from the appendicular skeleton, the comparisons are subject to question.
-The authors establish four pieces of evidence suggesting that the unIDed bone fragments belong to a giant ichthyosaur. They conclude that the combination of these features make the bone fragments unequivocally a giant ichthyosaur. 1) PSFT-I’m not convinced this is a novel tissue (see below), 2) strictly longitudinal vascular-very common vascular structure in medium-to-large-bodied vertebrates, 3) closely spaces skeletal growth marks structuring primary osteons and vascular canals-from what the authors have labeled on figures, I believe most of the time they are identifying cementing lines of secondary osteons rather than true growth marks, 4) abundance of secondary osteons inside primary ones-occurs in some titanosaurs which are not contemporaneous necessarily, but does occur more common than usually described. I don’t believe these features alone or in combination can necessarily reject alternative hypotheses.
-I think the authors should take care to not so unequivocally assign taxonomic status to these bone fragments and reject alternative hypotheses. While I do actually find it quite plausible that these fragments belong to a giant ichthyosaur, as presented, there is not enough support to reject alternative hypotheses. I believe these data are publishable, but it would require reframing the questions and conclusion of the paper.
In addition, I have the following comments that are somewhat more minor but should be addressed in a revised version.
-The templating deep cortex is slightly difficult to follow in the description. I believe I understand what the authors are describing, however, find it difficult to see the description reflected in the cited figures so I am unsure if what I think they are describing is the same as my interpretation. For instance, Lines 319-320 call to Figs. 3, which is too zoomed out to try and interpret this description of Fig. 4D which does not clearly indicated this templating deep cortex.
-It is not clear to me how the discussion of ‘templating’ contributes to their major conclusions/results. To me, it adds considerable density to the descriptions and I fail to make the connection between that concept and the taxonomic assignment.
-The discussion point of a potentially rare/unique bone type (if there is additional evidence that can support this claim) in the evolution of gigantism is interesting and I encourage this line of inquiry.
-I still have issues with the assignment of PSFT. I would encourage the authors to examine calcified cartilage literature as it appears in many of the figures quite similar. In fact, if the authors can reasonable conclude they are finding calcified cartilage in the unidentified bone fragments, this may be a more compelling piece of evidence to suggest an aquatic reptile as this can be seen in some semi-aquatic to aquatic vertebrates (e.g. Klein et al. 2019).
I do have major concerns with the data, analysis, and conclusions of this manuscript. That said, I think there are interesting points worth pursuing and these specimens are beautifully sectioned. I would encourage the authors to consider re-evaluating the data presented to address these concerns and/or the framework of the project and presenting these data.
The English is clear, the literature is thoroughly cited, and the study is self-contained. The histological images are at times unclear and below the current standards of the field (see my comments below)
Study design is adequate.
The findings are supported, pending the movement of supplemental text to the main text (see below)
This manuscript describes the bone histology of several fragmentary of large-bodied individuals from the Rhaetian of Europe and, using this description, identifies them as belonging to ichthyosaurs. It also introduces a new bone tissue type, termed periosteal structural fiber tissue (PFST). I have several major comments and numerous minor editorial comments in the attached PDF.
Major comments
1. I was surprised that a major (perhaps the major) portion of the text was placed in the supplement: the comparative bone histology of other large-bodied Triassic tetrapods (Article S2), ruling out the identity of the unidentified fragments as being anything other than ichthyosaurs. This is a very important part of the authors’ main argument, and there is no reason for it to not be in the main text. Similarly, the description of the studied specimens (Article S1) should also be in the main text, along with images of the sampled specimens. PeerJ has no length restrictions, so information crucial to the main thesis of the manuscript, and important methodological concerns, have no reason to not be in the main text. I would save the supplement for things like raw data (e.g., the binary photos, Fig. S6).
2. Imaging the histology by holding a cell phone camera to the eyepiece and stitching these images together is not the standard of the field, and produces what at times are subpar, difficult-to-interpret images (e.g., Fig. 5). I assume that the authors only imaged histology this way because of a lack of access to a microscope with an attached camera; regardless, this should be rectified by the next submission. Further, I am unsure as to how the scale bars were determined if the images were created by stitching together cell phone images together. Ideally, high-resolution full-slide images (at least the scanned images) should be included in the supplement or on an online data repository, as is becoming standard in paleohistological studies.
3. The authors use the term skeletal growth mark (SGM) throughout the text and figures, but I had trouble telling in the provided images what they were talking about. I suspect they are using this term different from how I assume (as a catch-all term for LAGs and annuli), but I’m not sure what they mean. I recommend they be explicit regarding the definition of this term. Clearer images will also help with this.
4. The authors need to provide more clear and explicit diagnostic criteria for PFST in the “New Terminology” section. As it stands, the description here is vague and only given in reference to other bone types. By the end of the manuscript I had a good idea what the authors meant by this bone tissue, and it is indeed very interesting, but they should be more clear up front because that is where readers (and re-readers) will turn when seeking to diagnose this tissue type in their own studies.
The authors are free to contact me with any questions or requests for clarification.
Chris Griffin
[email protected]
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