Evaluating Sexual Dimorphism in Postcranial Elements of Eurasian Extinct Stephanorhinus etruscus (Falconer, 1868) (Mammalia, Rhinocerotidae)

Round 1

Reviewer 1 Report

The reviewed work is an important study on the problem of studying sexual dimorphism in fossil forms. The incompleteness and fragmentation of the bone remains pose serious problems of interpretation. The skulls are much better studied, although there are not many such works, especially in rhinoceros. As the authors note, the situation is different in the case of the bones of the postcranial skeleton. Rhinos are an important group in the fossil record and therefore any research work on this group, and especially on the variability of the remains of the postcranial skeleton, is very important. The authors investigated the problem of sexual variability of the bones of the postcranial skeleton in Stephanorhinus etruscus, a basal representative of the genus Stephanorhinus. They did not select the humerus and femur for the analysis due to their more modest representation and a significant degree of fragmentation resulting from a lower fossilization potential. Likewise, they only analyzed whole, fully ossified bones. In my opinion, the methods used in the work are well selected and the selection of materials is appropriate. The authors examined the obtained results using statistical tests and presented them in tables and graphs. The obtained results indicate that the sexual dimorphism in this species is poorly marked on the bones of the postcranial skeleton. Only some measurements on some bones show this variability. Although the results are not obvious, I believe that the work deserves publication as it is an important contribution to the discussion and a guide for other authors to investigate other Neogene and Pleistocene rhinoceros species in this regard. Of particular importance for other researchers are the measurements of the studied species used in the work, included in the appendix. The results and discussion are very synthetically written, I understand that these are the requirements of the journal. The authors may have gone so far as to make more firm statements, or to mark in diagrams what they think suits females and what suits males, but they chose a more cautious approach. Congratulations on choosing a topic and taking up a research problem and publishing it. I have a question for the authors, how does this variability and distribution of dimensions look like in specimens with skulls, in which specimens are known to have belonged to males and which to females. Finally, I conclude that the work deserves to be published. I have no editorial comments. The choice of literature and its citation is correct.

Author Response

We thank the Reviewer1 for comments and statements reported in the "suggestions and comments for the authors".

Concerning the question: how does this variability and distribution of dimensions look like in specimens with skulls, in which specimens are known to have belonged to males and which to females?

Unfortunately we haven't complete skeletons with associated skulls; the mounted skeletons housed in the Natural History Museum of Florence (IT) are composite and derived from different individuals. In addition some specimens are mainly from old excavations and no data are available on the possible association between postcranials and skulls as in the case of Olivola. One skeleton from Pietrafitta (MGPLB) preserves a crushed skull without nasals (the most dimorphic area in Asian rhinoceroses), see figure in Pandolfi et al. 2017 CRPalevol; a mounted skeleton from Senèze housed at NHMB has the skull totally reconstructed.

Reviewer 2 Report

Title:  Evaluating Sexual Dimorphism in Postcranial Elements of Eurasian Extinct Stephanorhinus: the Case Study of S. etruscus (Falconer, 1868)

Better: Evaluating Sexual Dimorphism in Postcranial Elements of Eurasian Extinct Stephanorhinus (Mammalia, Rhinocerotidae): the Case Study of S. etruscus (Falconer, 1868)

Remarks:

In general, studies on postcranial bones and sexual dimorphism have been poorly evaluated or investigated in Pleistocene Eurasian mammals, such as rhinos, proboscideans etc. For example, the lengths of the limbs reflect the attribution to the genera: the lengthening of metapodials, especially of abaxial ones (which also serve as a reference material) shows the more cursorial genera than other genera in correlation with shorter humerus, femur and tibia.

In this respect the present study contributes to this, so it is interesting to be published. Although in the paper it is referred that both morphological and morphometric variability should be discussed, the present study focusses only on the latter, on the morphometric data. For a “classic” palaeontological study this discussion on morphological features, stratigraphy and taphonomy are missing (or better are poorly analyzed), therefore the morphometric elements of this study can be better evaluated by expert statisticians regarding the degree of accuracy and value of the results.

Concluding, the present paper can be marginally published with a major revision.

Text

• L99 etc., Better calcaneum instead of calcaneus
• L11 rugosity is something different, do you mean tuberosity (tuber calcanei is what we measure).
• Decide to use homogenously either MCIII/MTIII (L230) or MC3/MT3 (L75&L76). (Preferably Mc III / Mt III)

More remarks in the attached pdf and .doc files

geosciences-1635517-supplementary

1. References

The problem with the references by the names in the tables of measurements is that the reader cannot be informed easily for them because in the main text are not in alphabetical order. Therefore, it is suggested either to add a reference chapter with the names in order or to add the number corresponding to the references within the text. For example, it took me some time to try to find that many references

• Guérin & Heintz, 1971
• Guérin, 2004
• Santafè-Llopis & Casanovas -Cladellas, 1987
• Mazza, 1993,
• Mazza 1994,
• Mazza 1996
• Lacombat 2005
• Fortelius et al., 1993
• Fortelius, 1993
• Cerdeño, 1989

are missing (actually, all references are missing except one: Mazza et al. 1993).

1. Measurement abbreviations (page 3 in the main text): Better to accompany the corresponding supplementary tables, like it is in the tables of the main text. It is easier for the reader.

Comments for author File: Comments.pdf

Author Response

We thank the Reviewer2 for his/her work on the manuscript and the submitted comments.

Better: Evaluating Sexual Dimorphism in Postcranial Elements of Eurasian Extinct Stephanorhinus (Mammalia, Rhinocerotidae): the Case Study of S. etruscus (Falconer, 1868)

We changed the title accordingly.

Remarks:

In general, studies on postcranial bones and sexual dimorphism have been poorly evaluated or investigated in Pleistocene Eurasian mammals, such as rhinos, proboscideans etc. For example, the lengths of the limbs reflect the attribution to the genera: the lengthening of metapodials, especially of abaxial ones (which also serve as a reference material) shows the more cursorial genera than other genera in correlation with shorter humerus, femur and tibia. In this respect the present study contributes to this, so it is interesting to be published. Although in the paper it is referred that both morphological and morphometric variability should be discussed, the present study focusses only on the latter, on the morphometric data. For a “classic” palaeontological study this discussion on morphological features, stratigraphy and taphonomy are missing (or better are poorly analyzed), therefore the morphometric elements of this study can be better evaluated by expert statisticians regarding the degree of accuracy and value of the results.

We removed any reference to morphological characters, being this work only based on morphometric values. The taxonomic attribution of the considered specimens have been published within the papers cited in References. It is not the aim of this work to discuss taphonomy and stratigraphy but only to try to detect some kind of sexual dimorphism that could affect some considerations based on different approaches (size variations within the species for example). We added additional analyses on the Valdarno sample and we added a supplementary file with formulas used in the paper in order to allow reproducibility and additional tests on our sample. The values of the results obtained with the applied formulas have been discussed within the literature cited in methods. 

Concluding, the present paper can be marginally published with a major revision.

We hope the new revised version of the manuscript will clarify the doubts raised by Reviewer2.

Text

• L99 etc., Better calcaneum instead of calcaneus
• L11 rugosity is something different, do you mean tuberosity (tuber calcanei is what we measure).
• Decide to use homogenously either MCIII/MTIII (L230) or MC3/MT3 (L75&L76). (Preferably Mc III / Mt III)

More remarks in the attached pdf and .doc files

We thanks for the remarks and we accepted all the suggestions as it is possible to verify on the marked manuscript.

geosciences-1635517-supplementary

1. References

The problem with the references by the names in the tables of measurements is that the reader cannot be informed easily for them because in the main text are not in alphabetical order. Therefore, it is suggested either to add a reference chapter with the names in order or to add the number corresponding to the references within the text. For example, it took me some time to try to find that many references

• Guérin & Heintz, 1971
• Guérin, 2004
• Santafè-Llopis & Casanovas -Cladellas, 1987
• Mazza, 1993,
• Mazza 1994,
• Mazza 1996
• Lacombat 2005
• Fortelius et al., 1993
• Fortelius, 1993
• Cerdeño, 1989

are missing (actually, all references are missing except one: Mazza et al. 1993).

We added all the missing references within the supplementary file1.

1. Measurement abbreviations (page 3 in the main text): Better to accompany the corresponding supplementary tables, like it is in the tables of the main text. It is easier for the reader.

We added all the abbreviations.

Reviewer 3 Report

This manuscript evaluates the existence of sexual dimorphism in the rhino species Stephanorhinus etruscus, reflected on limb bones. This is an interesting work as postcranial skeleton is often subestimated in paleontological papers, even though limb bones can be numerous within fossil mammal assemblages. Therefore I consider this manuscript deserves publication. However, I have some comments on the way results are exposed.

I generally do not do statistical analysis and, so, I apologize for any methodological error I can have. I assume that the statistical treatment of the entire sample of material as a whole is correct, but I think that the results should be emphasized by partial samples. That is, histograms and bivariate plots reflect two clear clusters in many cases, but what really can be interpreted as sexual dimorphism is the sample of a single locality in which these two clusters are differentiated. This is the case of Valdarno, for instance, whose greater number of studied specimens reflects two well-differentiated clusters for almost all considered bones. Subsequently, other isolated or scarce remains that appear grouped in the plots with one or the other cluster can be then interpreted in the same way, but you do not actually know the variation of these other samples. My main comments in the PDF are directed in this sense (e.g., page 12). Other minor corrections or suggestions are also included.

Comments for author File: Comments.pdf

Author Response

This manuscript evaluates the existence of sexual dimorphism in the rhino species Stephanorhinus etruscus, reflected on limb bones. This is an interesting work as postcranial skeleton is often subestimated in paleontological papers, even though limb bones can be numerous within fossil mammal assemblages. Therefore I consider this manuscript deserves publication. However, I have some comments on the way results are exposed.

We thank Reviewer3 for his/her comments and suggestions.

I generally do not do statistical analysis and, so, I apologize for any methodological error I can have. I assume that the statistical treatment of the entire sample of material as a whole is correct, but I think that the results should be emphasized by partial samples. That is, histograms and bivariate plots reflect two clear clusters in many cases, but what really can be interpreted as sexual dimorphism is the sample of a single locality in which these two clusters are differentiated. This is the case of Valdarno, for instance, whose greater number of studied specimens reflects two well-differentiated clusters for almost all considered bones. Subsequently, other isolated or scarce remains that appear grouped in the plots with one or the other cluster can be then interpreted in the same way, but you do not actually know the variation of these other samples.

We performed the analysis on the Valdarno sample as suggested by Reviewer3 and we attached this analysis as Supplementary File2. The results are also discussed within the manuscript but they showed the limits of the applied methods on such poorly represented specimens.

My main comments in the PDF are directed in this sense (e.g., page 12). Other minor corrections or suggestions are also included.

We accepted all the suggestions reported by Reviewer3 on the manuscript as it is possible to check on the marked manuscript.

Round 2

Reviewer 2 Report