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Everything looks great, thanks again for your submission to PeerJ.
I'm happy with your responses to the external reviews. I have just a few, very minor suggestions that I will e-mail to you separately. Most are stylistic, and can be accepted at your discretion. These should take only a few moments of your time, and upon resubmission, everything should be set for acceptance.
Thank you for choosing to deposit your original scan data into Hyrda, and thank you for choosing PeerJ.
The reviewers are in agreement on the importance of this study, and have suggested varying degrees of revision. I’m recommending minor revision here, but in truth, there is a bit of work to be done. I don't believe that the revisions suggested below will alter the major points or descriptive nature of the paper, so for this reason, and upon your response, I'm hopeful to make a final decision without additional reviews. Please pardon the four(!) reviews, but do consider it as a positive statement on the interest in your study. I think they all added valuable comments.
I’ll highlight several points here broadly, but do please respond to all of the reviewers’ comments
(1) Thoroughly consider your language and discussion regarding evolutionary polarity of various anatomical structures within naked mole rats and their close relatives. Both reviewer #1 and #4 comment on this specifically in several areas of the manuscript, and I am in agreement that, at times, the language used is not consistent with previous knowledge. As the value of the descriptive aspect of this paper is clear, presenting likely scenarios of polarities is perfectly appropriate. Reviewer # 1 gives a good comment on how to handle these details in lns. 326-328
(2) Reviewer # 2 recommends more discussion on the relationship between anatomy and behavior (eating habits, etc.), and I agree that it would be preferable to have more discussion in that area.
(3) Please update some missed literature, particularly that mentioned by reviewer #4.
(4) Review #2 mentions a repository for the CT data. While I do not think MorhoBank would be appropriate for this type of data set, I do encourage the authors to consider depositing the slice data in something similar such as Dryad or Figshare. The 3D pdf is adequate, but more access would be ideal. Minimally, the data set should be deposited with the collection from which the specimens were obtained. On that point, you don’t seem to define CGF, please clarify this.
This is a great study, and I’m looking forward to seeing your response to the reviewers. Thank you for choosing PeerJ, with special thanks for allowing the open review process!
Figure 2 and 4 can be slightly modified.
I cannot watch the video (sup 2).
The interest of studying the cranial musculature of the naked mole-rat compared to other Bathyergidae should be redefined considering that this species does not necessarily represent the ancestral condition.
The authors should insist on the comparison between the naked mole-rat and other fossorial Hystricognathi.
This article dealing with the description of the masticatory muscles in the naked mole-rat contributes to a better understanding of the evolution of Bathyergidae and their adaptation to a fossorial life.
I have only a few comments and suggestions detailed in the PDF file.
See attached PDF.
See attached PDF.
See attached PDF.
See attached PDF.
This paper is an interesting and useful addition to the literature on the comparative anatomy of the masticatory muscles in rodents and mammals overall. The anatomical descriptions are good and the references to the published literature are appropriate. The paper is well organized and clearly written and I have no significant criticisms to offer.
Use of micro-CT with iodine enhanced contrast has proved to be a useful technique, and the present paper is one more demonstration of its utility.
I do have a couple of items for consideration by the authors.
1. (around line 208) The manuscript makes no mention of a posterior masseter muscle. A posterior masseter has been described in hystricognaths (Druzinsky Doherty, De Vree 2011; Woods and Howland, 1979; Woods and Hermanson, 1985) and Pedetes (Offermans and De Vree, 1989). I think it would be surprising to find that there is no posterior masseter present in H. glaber and other bathyergids but, if it is truly absent, I think that it is worth mentioning in the discussion.
2. (around line 291) I think that it is reasonable to believe that a fairly large temporalis muscle is the primitive condition for rodents. Although the number of species with relatively large temporalis muscles is small among the enormous number of extant species, I (Druzinsky, 2010) found that the temporalis in Aplodontia represents more than 30% of the total adductor muscle mass and in sciuromorphs the percentage was high, 25 to over 30%. I also suggested that a large temporalis-zygomaticomandibularis complex may be related to flattening and widening of the skull seen in burrowing, fossorial species.
The paper is a solid piece of work in general; however, I have a couple of reservations. First, the article does not discuss some important work on the morphology of the jaw muscles in bathyergids, namely, the work of Meinertz (Meinertz, T. 1951. Das Fazialisgebiet der Nager. VIII. Bathergini Winge, sowie einige Bemerkungen über Pedetes Caffer (Pall.) Morphol. Jahrb. 90:105-147.), who did describe the facial muscles of bathyergids. My concern is that the substance of the finding is just not different from what we already know of bathergids; namely, that they're functionally protrogomorph and that this morphology is likely secondarily derived. Second, the article is a bit misinformed where it comes to the comparator Aplodontia rufa, which has been established (Eastman, Charles B. 1982. Hystricomorphy as the primitive condition of the rodent masticatory apparatus. Evolutionary Theory 6:163-165.) to have a technically hystricomorph condition. This omission is a bit less problematic than the first for the publication of the paper.
There is nothing wrong with the experimental design itself other than that the question may not be all that meaningful in light of what we already know about bathyergid jaw musculature on the basis of past work.
The findings seem valid and well-supported.
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