The Tetrapod Fossil Record from the Uppermost Maastrichtian of the Ibero-Armorican Island: An Integrative Review Based on the Outcrops of the Western Tremp Syncline (Aragón, Huesca Province, NE Spain)

Round 1

Reviewer 1 Report

This is a highly valuable review of the very important fossil vertebrate record from the western Tremp basin of the eastern Pyrenees. As one of the few places in the world where faunal succession at the very end ot the Cretaceous can be studied, this area deserves to be better known, and this paper provides a wealth of information that will be useful to palaeontologists working on terminal Cretaceous faunas. The comparison with the Hateg basin of Romania is interesting, as it definitely suggests different faunal events during the Maastrichtian.

The paper can be published after minor improvements have been made, as listed below:

• the English should be improved. Although the paper is legible, there are many "Spanish" turns of phrases that should be corrected,and various small mistakes that should attended to, such as "meanwhile" instead of "while", "earlymost" instead of "earliest", etc. The help of a native English speaker  could be useful. On lines 386-387, about turtle plaston elements, the letter "y" has often been mistakenly replaced by the letter "i" (for instance "hipoplastron"). 'Crocodylomorphs" is often misspelled as "Crocodylimorphs".
• line 414: in France, upper Maastrichtian outcrops are not restricted to Haute-Garonne. The Fontjoncouse locality in the Corbières is in department Aude, much farther east than Haute-Garonne.
• line 416: the "Maastrichtian Dinosaur Turnover" was first reported and described in the following paper, which should be cited: 

  Le Loeuff, J., Buffetaut, E. & Martin, M. 1994- The last stages of dinosaur faunal history

  in Europe: a succession of Maastrichtian dinosaur assemblages from the

  Corbières (southern France). Geol.Mag., 131, 5: 625-630.

• A final general remark: as noted in the introduction, the faunal succession in the Tremp basin has a direct bearing on our interpretation of K/Pg extinctions. Yet the authors say little about this topic in the conclusion. A very important point in the debate about the causes and processes of the K/Pg extinctions is whether a decline in the diversity and/or abundance of some groups of organisms can be detected before the K/Pg boundary. Despite the various biases mentioned by the authors, it would be interesting to discuss, even briefly, this aspect.
• The figures are generally fine. However, figures 3 and 8 are illegible because the fonts are too small. A different layout may solve the problem.

Author Response

(Lines indicated are those from the Reviewer 1 comments, they might change in the new reviewed document)

• The text has been reviewed by a native speaker translator, who has improved the English of the text, and corrected the ‘Spanish’ turns and little semantic mistakes.
• We corrected all the misspelled 'Crocodylomorphs"
• We have discussed briefly what can we infer from the fossil record of the Ibero-Armorican island about the evolution of tetrapod diversity/abundance before the K/Pg boundary.
• We tried to solve the problem of legibility of figures 3 and 8. We increased the font size in figure 3, and we split figure 8 in several figures (Fig. 8 9 and 10), in order to facilitate their reading.
• Line 386-387_ We replaced the incorrect spelling of the plastron elements described by the proper one.
• Line 414_ We added the department of Aude in the areas of France with late Maastrichtian fossil sites
• Line 416_ We cited the suggested reference in that part of the text and removed [160], which was cited wrong there.

      [160]: Le Loeuff, J.; Buffetaut, E.; Cavin, L.; Laurent, Y.; Martin, M.; Martin, V.; Tong, H. Les hadrosaures des Corbières et des Petites Pyr_en_ées. Bull. la Société d’Etudes Sci. l’Aude 1994, 94, 19–21.

Reviewer 2 Report

This paper provides a review of the Maastrichtian geological units in northern Spain (Tremp syncline). It mostly reviews the vertebrate faunas from these units and makes comparisons with vertebrate faunas from other parts of Europe (mainly Hateg, Romania)

Overall it is useful to have these kinds of reviews of given units, so the paper is welcome.

I don’t have any major suggested changes.

If it is possible, it would be nice to see a few more images, either of specimens or of the taxa they represent. I know there is one figure of specimen images, but it would be nice to include more if images are available, or legal to use.

I’ve been through the manuscript in the PDF (see attached) and made quite a few suggested edits. 95% of these are corrections for language, with a few sentence rearrangements for clarity and conciseness. English is my first language, but I don’t pretend to be especially good at the technical side of writing; nevertheless I hope my edits will help the authors. There are a few places where the meaning of a sentence is not clear, so I have highlighted this and added a note.

If these edits are made the paper should be published. I suppose this probably constitutes minor edits.

I’ve made a note in one place about use of the term “diversity” (referring to species). It’s not a big deal in this paper, but as we get ever finer stratigraphic resolution it is becoming clear that many species are stacked into probable anagenetic lineages. A stack of chronospecies is not evidence of diversity – for “diversity” all the species must be contemporaneous. I see quite commonly authors claim that they look at “diversity” of a given clade within a formation, when they are merely counting species without considering the possibility of chronospecies. This has overinflated “diversity” estimations in many paleobiological analyses. Anyway, it’s not a huge deal in the current manuscript, I would just urge a bit of caution in using this kind of language. You can always say “there are a large number of defined species” for a given clade in a formation: this is merely a statement of data. Saying that a clade is “diverse” is an interpretation of the data.

Comments for author File: Comments.pdf

Author Response

(Lines indicated are those from the Reviewer 2 pdf document with comments)

• We have added the names of the authors in those cites in which they were required.
• As suggested, we figured more fossils in Figure 4, including theropod fossils and the pterosaur bone that we described in the text.
• Line 24_We have changed ‘propitiate’ for ‘led to’, which makes the meaning of the sentence clearer.
• Line 43_ We change ‘rising’ for ‘major’, which fit more with our intended meaning for the sentence.
• Line 63_ We eliminated ‘and references therein’ and cited the most recent review papers of the Spanish, French and Romanian record, since the parenthesis pretended to point some examples of several decades of research in these territories. Almost all the main concrete research is cited later in the text, so we preferred to not cite them in this part now.
• Line 70_ We did the same change than in line 63.
• Line 111_ We did the suggested paragraph breakings, starting a new one with each one of the sedimentary units, and pairing the Tremp Fm Cretaceous subunits in a paragraph, doing the same with the Paleogene subunits.
• Line 140_ We changed the term ‘sedimentary gap’ for ‘disconformity’.
• Line 141_ We understand that the sentence as it was written is confusing, so we modified it to make clear that the boundary would be situated in an interval that encompasses the last meters of the Lower Red Unit to the boundary with the Vallcebre limestones.
• Line 198_ We prefer to use ‘fossil remains’ instead of ‘individual specimens’ or ‘individual bones’, since the inventoried fossils include bones, tracks and eggshells.
• Line 259_ We decide to remove the autopodial bone/phalanx, since its condition is so fragmentary that even is assignation to Sauropoda is doubtful, and thus it blurs more than sheds light.
• Line 299_ We agree with the reviewer with the use of the ‘Fm’ abbreviation, and then we maintain its use in the text.
• Line 320_ We added the pterosaur bone to Figure 4.
• Line 382_ It is difficult to determine percentages of the stratigraphic position of fossil remains within the formations due their thickness is not constant throughout the Tremp Basin. So, we prefer to use this qualitative nomenclature, that though is not so precise, help to ubicate the record in a general way.
• Line 439_We understand and agree with the reasoning of reviewer 2 about anagenetic lineages conditioning the real diversity that shows the fossil record. Thus, we have tried to reduce the use of the term ‘diversity’ referring to fossil species when is difficult to determine if they were contemporaneous and we commented this factor as one of the possible bias for diversity in the discussion. We also tried to be more aseptic in our language, limiting ourselves to simply enumerate the defined fossil species.
• Line 583_ We have changed the term ‘hadrosaurid lambeosaurines’ by ‘lambeosaurine hadrosaurids’ throughout all the text.