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Review History for Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids

Version 0.2 (accepted)

· · Academic Editor

Accept

I am totally satisfied with the revisions, which I have checked- the authors are to be commended for a particularly fastidious and patient revision of the paper! This is a rigorous magnum opus that will be a boon to palaeontology. It is wonderful that PeerJ is publishing it.

Version 0.1 (original submission)

· · Academic Editor

Minor Revisions

The authors are to be commended on a rigorous, substantive body of work in this manuscript; it is certain to be well cited in future literature. The reviewers have all made constructive suggestions for changes and uniformly agree that it should be published, with these minor revisions. Please include a point-by-point Response to Reviewers with your revised MS. In particular, I agree that a wider consideration of heterochrony as a concept and in non-dinosaurs would improve the paper, as would illustration of "ontogenetic changes in the external morphology of the cranial bones, even if such changes are hypothetical".

Reviewer 1 ·

Basic reporting

This paper is generally well-written and accurate. I think that the sections of the anatomical descriptions dealing with ontogenetic change could be more consistently delineated from the remainder, however. Almost every element should have some differences – see, e.g., multiple papers on turtle ontogeny by G.S. Bever, alligator ontogeny by Vickaryous and Hall (2008, J. Morph.), Bhullar et al. (2012, Nature) on bird and dinosaur ontogeny and heterochrony, several papers my Maxwell on birds, the supplement to Bhullar (2012, JEZ B), Maisano (2002, JMorph), and several papers by Tarazona, all of which have extensive descriptions of bone-by-bone ontogenetic change in reptiles: turtles, crocodylians, birds, and squamates, respectively.
On this note, a table of ontogenetic changes in Parasaurolophus element-by-element and as compared to other hadrosaurs would be useful.
There is one persistent grammatical mistake – the use of a hyphen following adverbs describing adjectives, e.g., 727 “poorly-preserved,” 908 “similarly-interpreted”, twice in 1131, etc. throughout the manuscript.

Experimental design

The discussion of heterochrony needs some citations – at the least, Gould (1977) and Alberch et al. (1979). Additionally, it would be interesting to know whether overall skull shape change (not just in the crest) is decoupled from size between Parasaurolophus and Corythosaurus. This would allow a more nuanced approach to potential heterochrony in these forms.
Regarding the nasal cavity work, the endocasts are interesting and impressive. A few words about which parts of the cartilaginous nasal capsule the various chambers relate to would be welcome. Regarding the brain endocast, Gans (1980, JHerp), Bever (2005, Palaeo electronica), and Bhullar et al. (2012, Nature) among others addressed ontogenetic changes in reptile brains and braincases and will provide comparative insight to the changes described here. For instance, the (de)flexure and rotation of the brain during ontogeny is well-known in archosaurs.
In the section on the axial skeleton, a little more attention to potential ontogenetic changes would have been welcome, despite the poor preservation. In the appendicular section, a bit of comparison to changes in birds and crocodylians would be enlightening as to the generality of the transformations described in, for example, the pelvis.

Validity of the findings

Anatomical descriptions appear accurate and thorough. Histological descriptions are excellent. I would have liked to see a formal phylogenetic analysis at least attempted to place this animal as Parasaurolophus.

Comments for the author

This paper is thorough and interesting and certainly of interest to a number of audiences. It is, in its current form, a little myopic in its focus on the dinosaurian literature and could benefit from broader comparisons. Certainly the papers mentioned above on ontogeny and heterochrony in various reptiles (including dinosaurs!) should be considered. Erickson et al. (2012, Science) should probably be cited in the section on jaw mechanics. The discussion of heterochrony should reference foundational works on the subject and perhaps try to couch the potential heterochrony in hadrosaurs in the formal structure set out therein.

·

Basic reporting

See below

Experimental design

See below

Validity of the findings

See below

Comments for the author

Note from staff: The original comments from this reviewer did not make it into the system correctly. Therefore Dr Weishampel supplied comments direct to staff as per the text below:

>my review was very simple: The Farke et al. MS is spot- on, well written, and complete as far as the bony descriptions and the synthetic discussions go. The only thing I would ask them to spend some more time on is the issue of the S-Loop of the crest and its phylogenetic distribution - parasaurolophins don't have one (that is, they've highly modified the vestibule to make their entire crest) and corythosaurins have an S-Loop. That's about it. In lieu of an official review, I hope that this will suffice.

Reviewer 3 ·

Basic reporting

This paper provides a thorough documentation and discussion of an important and unique specimen of lambeosaurine hadrosaurid. It is very informative, containing new insights into the anatomy and life history of one of the most iconic, yet still enigmatic taxa. I have only a few remarks; otherwise, I recommend this paper for publication, with minor revisions.

Experimental design

No comments.

Validity of the findings

Title and line 3 of the abstract: “Hadrosaurs” is too imprecise, unless you mean Hadrosauria (sensu Wagner and Lehman 2009), which I don’t think you do. Thus, I advise to better use “hadrosaurid(s)”.

Page 3, line 49: Usage of “corythosaurins” should be replaced for “lambeosaurins”. As recommended by Sullivan et al. (2011): “According to to Article 37.1 of the International Code of Zoological Nomenclature (1999): When a family-group taxon is subdivided, the
subordinate name that contains the taxon that contains the type genus of the superior taxon is denoted by the same name the nominotypical name. Thus, given that “Corythosaurini” is a subdivision (tribe) of Lambeosaurinae coordinate with Parasaurolophini, the proper name of the tribe should be Lambeosaurini, not “Corythosaurini.” (Sullivan et al. 2001:406).

Page 8, lines 259 and 260. The terms “laterotemporal” and “dorsotemporal” are not how these opening are typically referred too and they seem like an odd choice. I’d recommend using the more common terms “infratemporal” and “supratemporal” fenestrae.

Page 9, line 281, 284: “naris”. It would be better to further specify that it is the “external naris” or “bony naris”.

Figure 6 and the premaxilla-nasal articulation: on Fig. 6 the nasal bifurcates ventrally to receive a finger-shaped process of the premaxilla. This configuration is similar to that of juvenile Corythosaurus (Evans et al. 2005:Fig. 18.1). It is not clear to me how could the authors derived with such detail this articular morphology from RAM 14000? As seen in Fig. 5, such articulation is nowhere to be seen (unpreserved?).

Page 34, line 1379 and following lines: Regarding the interesting discussion of the extent of the nasal and premaxilla in Parasaurolophus, I think the paper would be even more informative than already is if it included a figure showing ontogenetic changes in the external morphology of the cranial bones, even if such changes are hypothetical at this juncture, much like they did with the nasal passages in Fig. 11.

References


Evans D. C., Forster, C. A., and Reisz R. R. 2005. The type specimen of Tetragonosaurus erectofrons (Ornithischia: Hadrosauridae) and the identification of juvenile lambeosaurines. In: Currie PJ, Koppelhus EB, eds. Dinosaur provincial park: a
spectacular ecosystem revealed. Bloomington: Indiana University Press, 349–366.

Wagner, J. R., and Lehman, T. M. 2009. An enigmatic lambeosaurine hadrosaur (Reptilia: Dinosauria) from the Upper Shale Member of the Campanian Aguja Formation of Trans-Pecos Texas. Journal of Vertebrate Paleontology 29:605-611.

Sullivan, R. M., Jasinski, S. E., Guenter, M., and Lucas, S. G. 2011. The first lambeosaurine (Dinosauria, Hadrosauridae, Lambeosaurinae) from the Upper Cretaceus Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. New Mexico Museum of Natural History and Science 53:405-417.

Comments for the author

Title and line 3 of the abstract: “Hadrosaurs” is too imprecise, unless you mean Hadrosauria (sensu Wagner and Lehman 2009), which I don’t think you do. Thus, I advise to better use “hadrosaurid(s)”.

Page 3, line 49: Usage of “corythosaurins” should be replaced for “lambeosaurins”. As recommended by Sullivan et al. (2011): “According to to Article 37.1 of the International Code of Zoological Nomenclature (1999): When a family-group taxon is subdivided, the
subordinate name that contains the taxon that contains the type genus of the superior taxon is denoted by the same name the nominotypical name. Thus, given that “Corythosaurini” is a subdivision (tribe) of Lambeosaurinae coordinate with Parasaurolophini, the proper name of the tribe should be Lambeosaurini, not “Corythosaurini.” (Sullivan et al. 2001:406).

Page 8, lines 259 and 260. The terms “laterotemporal” and “dorsotemporal” are not how these opening are typically referred too and they seem like an odd choice. I’d recommend using the more common terms “infratemporal” and “supratemporal” fenestrae.

Page 9, line 281, 284: “naris”. It would be better to further specify that it is the “external naris” or “bony naris”.

Figure 6 and the premaxilla-nasal articulation: on Fig. 6 the nasal bifurcates ventrally to receive a finger-shaped process of the premaxilla. This configuration is similar to that of juvenile Corythosaurus (Evans et al. 2005:Fig. 18.1). It is not clear to me how could the authors derived with such detail this articular morphology from RAM 14000? As seen in Fig. 5, such articulation is nowhere to be seen (unpreserved?).

Page 34, line 1379 and following lines: Regarding the interesting discussion of the extent of the nasal and premaxilla in Parasaurolophus, I think the paper would be even more informative than already is if it included a figure showing ontogenetic changes in the external morphology of the cranial bones, even if such changes are hypothetical at this juncture, much like they did with the nasal passages in Fig. 11.

References


Evans D. C., Forster, C. A., and Reisz R. R. 2005. The type specimen of Tetragonosaurus erectofrons (Ornithischia: Hadrosauridae) and the identification of juvenile lambeosaurines. In: Currie PJ, Koppelhus EB, eds. Dinosaur provincial park: a
spectacular ecosystem revealed. Bloomington: Indiana University Press, 349–366.

Wagner, J. R., and Lehman, T. M. 2009. An enigmatic lambeosaurine hadrosaur (Reptilia: Dinosauria) from the Upper Shale Member of the Campanian Aguja Formation of Trans-Pecos Texas. Journal of Vertebrate Paleontology 29:605-611.

Sullivan, R. M., Jasinski, S. E., Guenter, M., and Lucas, S. G. 2011. The first lambeosaurine (Dinosauria, Hadrosauridae, Lambeosaurinae) from the Upper Cretaceus Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. New Mexico Museum of Natural History and Science 53:405-417.