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Peer-Review Record

Vertebrate Skeletal Remains as Paleohydrologic Proxies: Complex Hydrologic Setting in the Upper Cretaceous Kaiparowits Formation

Geosciences 2025, 15(7), 262; https://doi.org/10.3390/geosciences15070262
by Daigo Yamamura 1,2,* and Celina Suarez 2
Reviewer 1:
Reviewer 2:
Geosciences 2025, 15(7), 262; https://doi.org/10.3390/geosciences15070262
Submission received: 1 May 2025 / Revised: 8 June 2025 / Accepted: 2 July 2025 / Published: 8 July 2025
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

All comments, issues to be addressed and proposed corrections can be found as comments in the manuscript. Overall, the manuscript need major revisions including rewriting of some sections that contain too many repetitions (Geological settings), the diaganesis section that is difficult to understand and needs to be improved, the delta symbol that is omitted many countless times throughout the text, and unsupported statements (see diegenesis sections). 

Concerning the supplementary materials, I would have expected more information that just trutle and the raw isotopic values. I would consider crucial to provide at least taxonomic attribution, stratigraphic position, locality data, material analyzed (dentine, enamel, bulk tooth, bone... It is particularly important to provide as much metadata as possible to comply with the FAIR data principle, so they can be reused in the future (and the paper more cited !). 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

As English is not my native language, I will not comment on it, but I checked the box that the quality of english must be improved, because geochemistry terminology was not properly used in some sections and needs to be corrected. 

Author Response

Thank you very much for the constructive feedback.  Response to comments are in the pdf attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper offers valuable insights; however, refining the narrative and addressing the suggestions outlined below would significantly enhance its clarity and overall impact.

General Suggestions:

Visuals: Consider including a map showing the sample locations and a conceptual diagram illustrating potential hydrologic influences on isotopic composition. These additions would help contextualise the data and improve interpretability.

Clarity: Define all abbreviations (e.g., SMOW, VPDB) upon first use to ensure clarity for a broad readership, particularly those from adjacent disciplines.

Interdisciplinary Links: Strengthen the discussion by exploring how the isotopic findings might inform broader questions such as dinosaur migration patterns or niche partitioning.

Typographical Consistency: Correct the minor typographical error “d¹⁸O” to “δ¹⁸O” for consistency with standard isotope notation (e.g., lines 49, 76, 110….).

Introduction

  • The background on stable isotopes is thorough, but the connection to the Kaiparowits Formation could be stronger. Add a sentence explicitly linking global isotope trends to the Kaiparowits Basin’s uniqueness.
  • Write a sentence to explain how diagenesis specifically affects δ¹⁸O in bioapatite, and why is phosphate more resistant than carbonate?

Geologic Setting

  • The stratigraphic breakdown is useful but could benefit from a visual (e.g., a simplified stratigraphic column).
  • Include a table summarising units (Lower, Middle, Upper) with key features (e.g., tidal influence).
  • does the volcaniclastic member (Beveridge et al., 2020) impact isotopic interpretations?

Materials and Methods

  • Sample preparation is well-described, but statistical methods lack detail. Clarify why Wilcoxon tests were used instead of t-tests for non-normal data.
  • Were any samples excluded due to diagenetic alteration, and how was this assessed?

Results

  • The high variability observed in crocodile δ¹⁸Oₚ values is not fully addressed. The Results section would benefit from a discussion of potential contributing factors, such as habitat heterogeneity or taxonomic distinctions.
  • Additionally, while no correlation is found between δ¹⁸O_c and δ¹⁸O_p in hadrosaurs, weak correlations in reptiles suggest a more nuanced relationship that warrants further exploration. Clarifying these patterns could provide deeper insight into paleoenvironmental interpretations and the effects of diagenesis

Discussion

The diagenesis section is well-developed; however, the paleoclimate discussion would benefit from a more thorough integration of relevant prior studies. Further elaboration on how diagenetic alterations may specifically bias paleohydrologic interpretations would enhance the analysis. For instance, could early diagenesis account for the observed lack of correlation between δ¹⁸O_c and δ¹⁸O_p values in hadrosaurs?

  • The deviation from Amiot et al.’s global δ¹⁸Op-latitude trend is highlighted, but alternative explanations (e.g., taxonomic biases, metabolic rates) are underexplored.
  • High variability in crocodile δ¹⁸Op obscures taxonomic comparisons, but the paper does not explore stratigraphic or taphonomic controls on this variability
  • I also suggest comparing Kaiparowits δ¹⁸O values directly with other Campanian formations if possible.
  • δ¹³C differences are attributed to diet but lack comparison with plant δ¹³C data from the Kaiparowits Formation.
  • The link between hydrology and dinosaur endemism is speculative. Expand the discussion to propose testable hypotheses (e.g., "If Mogollon runoff caused low δ¹⁸Op, then coeval basins without highlands should lack this signal") and suggest future studies to address them.
  • an explanation is needed on how the "monsoonal condition" hypothesis reconciles with the low δ¹⁸O values.

Conclusions

The conclusions are supported but could emphasise broader implications (e.g., dinosaur endemism). Add a sentence on how these findings inform future studies of Laramidian ecosystems.

Author Response

Thank you very much for the constructive feedback.  I have made edits following your feedback as much as possible for the given time.   The following are additional responses to some of the comments.

-The museum asked me not to disclose the sample locations while I was working on the dissertation, and I assumed that is still the case.

-One of the comments on geologic setting section asked about the volcaniclastic member's impact on isotopic interpretation. I assume there isn't an impact on isotopic compositions as all samples analyzed are 100+ meters below the volcaniclastic member.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have applied the requested corrections and taken into account my comments on the earlier version of the manuscript. I will be happy to see this paper published. 

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