Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland^†

Round 1

Reviewer 1 Report

The presented paper is a welcome contribution, presenting the description of a new taxon from the Triassic of Greenland. The specimen is described based on a superb work of tomographic segmentation, following recent workers. Additionally, authors provide a dispersal hypothesis for Plateoasauridae, based on the similarity with Brazilian taxa, contrasted with chronological and geographical differences. Overall, this represents an interesting contribution for early dinosaur paleontology, especially concerning Sauropodomorpha. Please note some minor comments, suggestions and queries, made in the hope of contributing to the quality of the manuscript.

Following recent contributions, I strongly recommend tht the authors provide stls or other ways of visualizing the generated 3D models, and cite them in the text. This can be accomplished by a series of online plataforms and repositories, and may increase the reach and replication of the analyses and data. 

Comments for author File: Comments.pdf

Author Response

We would like to thank the reviewer for the feedback that greatly improved the manuscript. All of the author's responses to the inquiries are found in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

The MS by Beccari et all provides the long-waited description of the Jameson Land plateosaurs. It is well written and executed, with no major flaws I could spot. In my opinion, the MS should be published after addressing the few (but important) comments provided below, as well as those included in the marked PDF.

Please, attempt to provide the complete name, not only the generic epithet, of all mentioned species.

When indicating the specimens of a particular taxon, please include the collection number under brackets; e.g. Unaysaurus (UFSM 11069).

In several parts (e.g.: lines 298, 1091, 1130, 1139, and 1142) the term “synapomorphy” is employed for the traits that unite NHMD 164741 and NHMD 164758. Although they can be somehow understood as such because they unite two OTUs of the analysis, it is incorrect to use “synapomorphy” for a single species (which they turned out to be). So, see the marked PDF and change for “autapomorphy”, or simply “apomorphy” as required.

In lines 349-355 it is not clear which specimens possess a gap between the rostral end of the premaxilla and the first premaxillary tooth. As written, it seems that there is no gap in NHMD 347 164758 (line 351), neither in Plateosaurus (line 354) or in MSF 15.8B (line 355). Please clarify.

Do not use the term “ramus” for entire jaw elements as in lines 406, 407, and 446.

The degree sign “°” is wrongly typed as “^o”.

In line 763 it is said that the parasphenoid process is disarticulated. This implies that the element was not completely co-ossified to the basisphenoid. In this case, it would correspond to a different bone, the parasphenoid per se, and would have to be described in a separate section. Yet, the process is most probably broken, not disarticulated, forming a single bone (even if with different origins) with the basisphenoid. In this case, the bone is better termed parabasisphenoid. BTW, these are always single bones, having no right-left antimeres (line 762).

In lines 1058-1066, it is not clear if the “slender bone fragments” represent parts of a single hyoid bone (in this case: is it the left or right?) or if they could be parts of the two elements. Please explain.

In lines 1194-1195 you say that “NHMD 164741 differs from NHMD 164758 in having a promaxillary fenestra”. At the same time, in line 1187-1188, you say that “both specimens received the same scores for every coded character in the phylogenetic analysis”. So, there is no character related to the presence of a promaxillary fenestra in the analysis? Please confer.

It would be very useful if reconstructions of the dorsal and palatal view of the skull were provided in Figure 38. Please consider including those.

In line 1237 (see also line 1312), you say that “NHMD 164758 shows only 18 tooth positions in each of its dentaries, and NHMD 164741 preserves a maximum of 18 tooth positions” and that the latter “could have reached at least 20 teeth when complete” (lines 1239-1240). So, did you mean “minimum” instead of “maximum” in line 1237? If so, please modify; if not, please provide a more comprehensive explanation.

In lines 1319-1320, you say that “Unaysauridae was not recovered in the phylogenetic analysis”. Yet, Unaysauridae was defined by Müller et al. (2018) as the most inclusive clade including Unaysaurus, but not Plateosaurus nor Saltasaurus. As such, it corresponds to the clade encompassing Unaysaurus and Macrocollum in your figure 36.

The most problematic issue with this MS is its section 5.4. Putting is shortly, my suggestion is that it should be completely excluded. This is due to the problems highlighted below, but also because it provides no crucial data for the MS, which stands strongly as a valuable piece of with without the “paleobiogeographic and chronological implications”.

All discussion in biogeography should be backed up by the phylogenetic results. As such, Issi saaneq is not more closely “corelated” (see line 1323) to the Brazilian plateosaurids than Plateosaurus is, and no biogeographic inference should rely on that. See also that Plateosauravus is not “closely related to the plateosaurids” (as mentioned in lines 1271-2172). You could say that, along with the German Ruehleia, it is close to the minimal clade including Plateosauridae and Massopoda, that’s all. Also, if Jaklapallisaurus is an Unaysauridae, it suggests that the family expanded its occurrence to India; it dos dot indicate anything about the dispersion route of other plateosaurids. So, unless this section is completely re-written, my advice it that it should be excluded with no to loss to the MS relevance.

Comments for author File: Comments.pdf

Author Response

We would like to thank the reviewer for the feedback that greatly improved the manuscript. All of the author's responses to the inquiries are found in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

All required changes were provided.