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Thank you for your diligence in addressing the concerns of the reviewers. I am satisfied with the revised manuscript, and I am happy to accept it for publication in PeerJ -- with the caveat that there is still room for improvement. I'm including a few recommendations here. I don't think they are major enough to warrant another round of review, but I do think they would improve the paper.
- In the abstract you mention, "the Diplodocid genus Diplodocus". When 'diplodocid' is used as an adjective, it should not be capitalized. It should only be capitalized when referring to Diplodocidae, the proper noun that is the name of that clade.
- I agree with the reviewer that the sub-pieces of skin would be much easier to keep track of if they were identified A1, A2, etc. instead of Ab, Ac, etc. The compound letters are recommended for PeerJ figure parts, not for identifying parts of specimens.
- I think the writing could be tuned up a bit by the old trick of reading the paper out loud, and seeing which sentences sound awkward.
- I assume that in Figures 11 and 12, north is to the top of the image? It would be good to have the orientation signaled with either an arrow in the figure, or a line in the caption ("north is to the top of the image" or similar).
- Similarly, which compass direction is the camera facing in Figure 2? Please make the facing explicit in either the figure or the caption.
- Finally, I strongly recommend that you add a figure, similar to Fig. 11b, that shows all of the skin patches, not just A, B, C, but the sub-parts A1, A2, etc., so that readers can get a better understanding of how all of the parts relate to each other and to the other things in the quarry, without any interpretation overlaid.
The decision of whether or not to publish the peer reviews alongside the paper is entirely yours, and will not affect how your paper is handled going forward. However, I encourage you to do so. Making the reviews public allows the reviewers to receive credit for their efforts, and also contributes to the emerging culture of fairness and transparency in editing and peer review.
[# PeerJ Staff Note - this decision was reviewed and approved by Laura Wilson, a PeerJ Section Editor covering this Section #]
Even though the skin (or skin impression? -- see reviewer comments) is still in the ground, I think it's okay to move forward with a preliminary description, provided that you can address the reviewers' concerns regarding its mode of preservation, identity, and relationship (or lack thereof) to the nearby bones. I've carefully considered the reviewers' comments and they all seem apt to me, and also tractable in terms of revising the manuscript. I look forward to seeing an improved version of this work soon.
No comment
No comment
No comment
This was simple and concise reporting, and I am glad to see a student conducting and publishing their very own research. Tess should be very proud of her accomplishment. Documenting scale morphotypes in these small-statured diplodocids will be an important contribution towards further documenting and better understanding dinosaurian integument.
The science here is good and the authors clearly made an effort to address the (apparently minimal) changes requested in prior review. I have mostly just a few comments related to readability of the text (see general comments, below). If I have one nitpicky issue, though, it would be the quarry map. I’m not sure it’s quite as good as it could be (maybe it is, I’m not party to all the info) – it just seems like a rather large area of uncertainty. It might also be useful to zoom in on the region of interest if possible – you can still have the whole map in the corner with a box indicating the zoomed in area, but I’m actually curious as to what variety of things are already mapped from the region of interest. I think the other figures are good, particularly given the difficulties of photographing things in the field and photographing things with relatively low relief. The one exception might be figure 9, in that it would be more helpful to know what part of the croc hindlimb we’re looking at – is that the trunk/limb transition that has the narrow, arching rows of scales? Is it the inside of the knee?
no comment
My one comment on the science is that while I think it’s probable that the rib and the skin are not associated, is it also not plausible that the carbonized skin simply eroded away, was removed accidentally in the excavation, or was not preserved from the surface of the rib? Are we looking at the internal or external surface of the rib?
Line comments:
Line 59 – I guess I would just make the note here that this is a “proposed” reason (perhaps “interpretation” is a better word)– I don’t know that it’s ever going to be possible to definitively prove it, even if the reasoning is pretty solid.
Lines 81-83 – unless this is a journal specific thing (I don’t think it is), I would just include the figure permissions in the caption for the map. I would also omit the second sentence as it is already assumed.
Line 87 – I’d make a figure reference here, at least to figure 2.
Line 90-92 – Again, I’d just omit this as it largely repeats the first sentence in the paragraph.
Line 109-110 – This repeats line 87.
General comment on the text in this section – I’d caution against using generic terms like “side” because it is not immediately clear which sides you mean – superficial/deep, anterior/posterior, etc. Please use specific terminology if possible.
Line 135 – “fetal”, perhaps
Line 140 – I’m not sure “diverge” is the right term here – perhaps “transition”?
All comments on manuscript. Some spelling and awkward wording issues.
All comments on manuscript.
Might be helpful to describe scale/tubercule types under headings and up front before describing the distribution of them on the skin patches.
Also, more direct comparison of the new types with previously described sauropod and more specifically diplodocid types would be preferred.
Other comments on manuscript.
All covered above or on the ms.
See general comments.
See general comments.
See general comments.
Many thanks for the opportunity to review this manuscript. Unfortunately at this time I cannot recommend it for publication, for several reasons:
• I do not think it’s acceptable to publish on a specimen that is still in the ground when there are plans to excavate it in the future (vs. a scenario where the specimen cannot physically be excavated at all).
• The hypothesis that these skin impressions belong to a juvenile Diplodocus is not adequately supported yet, and alternative hypotheses are not investigated and rejected.
• In general, the manuscript needs to cite the dinosaur integument literature more extensively throughout.
I realize that the Covid-19 pandemic likely plays a role in my main concern about the specimen remaining unexcavated, which is really unfortunate. I know that this was raised by the editor prior to sending this to me to review, but I don’t find the current stated plan to excavate at an unidentified point in the future sufficient. If latex moulds of the specimen had been collected (e.g. as for the Dragon’s Tomb Saurolophus skeletons that remain partly in situ), or photogrammetric models collected, I might feel differently, but right now all we’re working with are field photos of partially exposed material. What if you can’t return to the site before the specimens degrade? I think this manuscript just needs to wait until the skin is physically collected and in a repository.
Despite this, I’ve taken a pass through the manuscript and have offered some suggestions for improvement for moving forward with the manuscript eventually. My other critique regards the identification of these skin impressions as belonging to Diplodocus – that seems reasonable at first glance given the predominance of Diplodocus in the quarry, but alternate identifications should be considered and you should attempt to reject alternate hypotheses. You should also consider whether or not the skin impressions could represent a region of an adult sauropod’s body in more detail, as identifying these as infant sauropod skin impressions is also a fairly bold claim that needs to be backed up with more evidence than is currently presented. I think your discussion of scale size is compelling and it would be good to see this expanded on by perhaps building a table of measurements of scale sizes in other dinosaurs with known skin impressions, either through a literature review or museum trips.
The reference list is currently very short and limited and I would strongly encourage the authors to dive into the literature on dinosaur skin impressions in much greater detail, including more references to scaly integument records outside of Sauropoda. The preserved integument is also variously referred to as a mould and as carbonous, which I think means carbonized or carbonaceous. This seems somewhat contradictory, as what I think we’re looking at is either a natural cast of the skin or the fossilized skin itself. This also warrants further discussion or investigation. In general, the manuscript could also use a bit more polishing, as there are several sentences that are either extremely vague, require citations, or have awkward phrasing.
I wish the authors luck in getting these specimens out of the ground in the near future (with hopefully few delays because of the pandemic!), and revising the current version of the manuscript.
A few things need to be clarified with respect to the skin molds and other fossils from the site:
1. I know that the skin molds are still in the ground, and that the plan is to extract them later. Please state explicitly the plan for accessioning them into an accredited, publicly-available museum collection. I assume that there is such a plan, since privately-held fossils cannot be published in PeerJ. Perhaps the skin molds could be assigned field numbers, and provisionally accessioned? In concert, photographs and perhaps even photogrammetric models could be accessioned to a museum's digital collections. In particular, photogrammetry might be a useful hedge in case the skin molds are damaged during collection. (I realize you can't run out and get the necessary photos right now, that's a hopefully-helpful suggestion for the future.)
2. In line 78 you wrote, "The skin molds (MDS-2019-028) were found in proximity to two dorsal ribs". I understand that the biological association of the skin with the ribs is uncertain, but for posterity it would be useful to associate the skin with the ribs at least taphonomically. Have the ribs been collected, accessioned into a museum collection, or received field numbers? If so, it would be useful to include that information.
3. Is there a quarry map that could place the skin molds in context relative to current or past excavations? If so, it would be helpful to include it as a figure.
4. I think the wrong permit was accidentally uploaded with the manuscript. The filename says "2019_Collecting_&_Excavation_Permits_-_BLM_(MT)" but the content is a Special Recreation Permit to take visitors out to the site, and section C(4) prohibits the removal of fossil specimens unless specifically authorized by a separate permit (presumably a surface collection or excavation permit). Please upload the collecting and excavation permit with the revised manuscript. It might be useful to explicitly state in the Materials & Methods that collecting at the site was covered by a BLM permit issued to one of the authors or a colleague.
Hopefully none of these requests is too onerous. You have some really interesting fossils, and I look forward to seeing an improved version of the manuscript in the near future.
[# PeerJ Staff Note: Please note that this submission has only been reviewed by the Academic Editor at this point. Once you have addressed their comments, it will still need to be sent out for peer review. #]
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