Review History


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Summary

  • The initial submission of this article was received on December 21st, 2016 and was peer-reviewed by 3 reviewers and the Academic Editor.
  • The Academic Editor made their initial decision on February 5th, 2017.
  • The first revision was submitted on March 5th, 2017 and was reviewed by the Academic Editor.
  • A further revision was submitted on March 13th, 2017 and was reviewed by the Academic Editor.
  • A further revision was submitted on April 26th, 2017 and was reviewed by the Academic Editor.
  • The article was Accepted by the Academic Editor on April 27th, 2017.

Version 0.4 (accepted)

· · Academic Editor

Accept

I was asked to handle an Appeal on this manuscript.

I have had the time to review all submission and appeal material associated with the article “New Data Towards the Development of a Comprehensive Taphonomic Framework for the Late Jurassic Cleveland-Lloyd Dinosaur Quarry, Central Utah”, Peterson et al., and am now ready to make my decision. I outline below my overview and opinions of the requested revisions and author responses. Please note I do not include comments related to minor editorial remarks.
The initial decision was ‘Minor Revisions’ based on the agreed assessment of three external reviewers and PeerJ’s handling editor, Dr. Piñeiro. After resubmission, Dr. Piñeiro maintained the ‘Minor Revision’ status of the manuscript, and offered additional editorial remarks without sending the article out for more external review. Upon that resubmission, Dr. Piñeiro, offered additional editorial remarks, maintained the ‘Minor Revision’ status, and did not send the article out for additional external review. At that time Dr. Peterson submitted an appeal to you requesting that the article be referred to anther handling editor due to the perceived impasse between the authors and Dr. Piñeiro.

In the initial round of reviews the reviewers and editors agreed that the primary issues that needed better resolution were (1) improved image quality, including providing images of quarries, (2) characterization of bone fragment abrasion, (3) interpretations of dinosaur bone transportation to CLDQ, and (4) the source of the heavy metal signature. In their response, the authors revised figures, paying particular attention to better illustrate various IBFs, which helped to resolved issues (1) and (2) above. They did not provide quarry images, stating they do not have broad images of the site. They specifically made reference to their clarification as to mechanisms of bone transportation (3), stating they were not suggesting this was a crevasses splay. To point (4), they reference additional chemical analyses that are planned, and indeed, reviewer 1 suggests that additional chemical analyses are beyond the scope of this work. They also discuss various potential sources of the signature heavy metals.

Upon Dr. Piñeiro’s review of the resubmission material, she made additional requests for revision, that included: (1) a pointed, extensive request for images of the quarry, (2) a request for clarification about the authors statement concerning the time averaging at CLDQ, (3) a revision of figures showing concretions on bones, and (4) a request to better explain the origin of heavy minerals, with attention paid to alternative hypotheses. In response to this review, the authors included new or revised images to directly responded to points (1) and (3). The authors also discussed their interpretation of time averaging based on IBFs (2), which is newly applied to this site, and is consistent with previous whole bone interpretations. To point (4), the authors point out that while they had previously discussed other possible origins of heavy metals signatures, they do add an additional paragraph discussing how local mining may have contributed to these signals.

After the authors resubmission, Dr. Piñeiro’s primary three remaining concerns are that (1) aspects of the interpretation of depositional environment (2) the interpretations of time averaging at the sites, and (3) that the interpretations of the heavy metals are not correct. At this point, the authors requested an appeal of the Dr. Piñeiro’s decisions, reviewed by a new editor. They also submitted a mark-up version of the manuscript responding directly to Dr. Piñeiro’s most recent requests, and a response statement.

I believe that these lingering three primary requests had either already been adequately addressed by the authors or are based on a misreading of the manuscript by Dr. Piñeiro. More specifically, it is unclear in what ways Dr. Piñeiro would like further discussion of depositional environment. This is discussed well in the manuscript. As outlined by the authors, they are basing their time-averaging hypothesis on IBFs and 1,000s of specimens, not five, as suggested by Dr. Piñeiro. Given the way in which these were collected via quarrying, it is clear that IBFs are not a product of recent weathering, for example. I feel that the authors have done a commendable job discussing various aspects of heavy metal origins, and that this portion of the manuscript is reasonable and adequate. I also feel that the authors have done a thorough job describing alternative hypotheses regarding the origin of their heavy metals.

My recommendation is that PeerJ accept this manuscript for publication. Given the long editorial history, I also recommend that the authors resubmit a version in which all minor editorial comments have been incorporated, but that larger discussions and interpretations of time averaging, geochemical analyses, and depositional environments are reported as presented in the last version of this manuscript.

In short, I agree with all three reviews and the original editor in that this manuscript offers new and important information about the taphonomic history of CLDQ. The authors have done an admirable job addressing reviewer and editor comments, and I believe all involved offered sound and helpful comments with the best interest of this research in mind. Indeed, Dr. Piñeiro’s persistence has made this a much-improved manuscript, in particular. However, I feel that the manuscript, in its current form, meets PeerJ’s editorial criteria.

I just wanted to thank you for submitting your manuscript to PeerJ, and for your patience during this prolonged review process. I have included in my decision a marked-up copy of your most recent version that includes small minor corrections and limited syntax suggestions. Please incorporate the later at your discretion. I also hope that you thoroughly read through your references cited, figure captions, and figures once more for errors.

I would also like to encourage you to choose an open review for your manuscript. Open review, and the transparency it creates, is one of the primary reasons I am an editor at PeerJ. I think it's good for our discipline and colleagues to see the review process from the inside, particularly when it involves reviews that are mediated such as yours.

Version 0.3

· · Academic Editor

Minor Revisions

Dear authors,

I have reviewed your manuscript and found that it has several inconsistencies and unfunded statements that need to be fixed. I have included some improvements of grammar and several comments about the issues that I understand have to be modified, explained or referenced. I really think that this manuscript is indeed a very important innovation for the taphonomic study of potentially attritional, but apparently catastrophic deposits. But it is based at the time on non-well supported evidence, an issue that in my concept can be easily fixed.

Below, I will resume the main of my concerns.

Definition of your inferred depositional environment: this important aspect of your manuscript is dispersive. You are repetitive in some places and not concrete if a) the model that you propose is similar to those already suggested (e.g. that from Gates, 2004) or it may be similar but with some differences or is completely different. I have seen that your argumentation for to propose a shallow pond where the carcases were incorporated gradually to the sediments (attritional assemblage) is weak. If you have more evidences (maybe for paleosoils development in between the different flood events, or other). Maybe this can be also due to the bad photographies of the fragments that you provided, but my concern is basically that the five fragments that you describe are not enough proofs for to make a strongly supported hypothesis about their origin.

The time of origination of the small bone fragments. You decided to discharge the possibility that the fragments were recently incorporated to the matrix, but you have not provided enough evidence to sustain that the bones were fragmented before they were buried. Perhaps you have a lot of fragments of a single bone; you cannot state such conclusions from five or six very small fragments of bone! As you should know, the carcases suffer strong postmortem destructive processes, so, which had the opportunity of preservation, will also has been buried.
The images that you provide of the small bones are not very helpful, and it is hard to see the abrasion degree that you refer. To me, these fragments are highly angled and display sharp edges. The lack of high quality images of the outcrops, difficult closer analyses. I am glad to see that you could provide some images of the sites, but they are indeed out of the quality required by the journal. I will have to discuss their inclusion with the PeerJ editorial staff.

# Note from PeerJ Staff: Our articles can include an unlimited number of high resolution color images, so if the authors wish to provide better or additional images, this isn't an issue from our point of view #

The analysis of the present heavy metals is not correct, or need to be refreshed. To complement your assumptions, you should present a comparative data, where you can provide biochemical results from the isolated small bone fragments and the surrounding matrix (as in Fig. 6) which should also include updated results from the complete or semicomplete bones that remain in the sites and of course should be the source of the small scattered fragments (presuming to come from both CLDQ and MMQ; this is also not well specified in the ms.), and should include the microvertebrates (meaning teeth or other elements, as turtle carapace fragments).

Hoping that these recommendations and suggestions are considered useful to you, I very look forward to see the new version of the manuscript submitted very soon.

Kind regards,
Graciela Piñeiro

Version 0.2

· · Academic Editor

Minor Revisions

Dear Dr. Peterson,

I received the new version of your manuscript and I think that it was improved by following the reviewer’s recommendations, but not enough to be ready for publication yet.

Please see below my comments (in red, in the pdf file attached) regarding your answers and provide a new version of your manuscript or a rebuttal letter explaining your points of view.
With my best regards,

Graciela Piñeiro

Editorial Comments:

It could be very useful to your manuscript that you provide photographs of the quarries, showing a general view of the outcrops and also of the bone beds that you studied. Taphonomic studies require high quality and informative imaging to show what you are describing and interpreting, even more when you are suggesting a new taphonomic hypothesis. I could not see the phosphate crystallites from your figure 7. JP: Figure 7 has been revised to include better images of the thin section. Upon further analysis of the improved image with a better microscope and computer, the mineral in-filling appears to be pyrite. The manuscript has been updated to reflect this revelation. It could be also interesting that you can provide detailed images of the studied deposits and the compared bone beds. JP: Unfortunately we do not have any photographs of the JONS site that would be usable for demonstrating details of the outcrop. This site is being planned for further future study and will include more detail later.

GP- I cannot imagine the situation here. You decided to perform a taphonomic study and you did not take any photographs of the site and the fossils? You have just seen the outcrop and from memory you are describing it? Thus, you are talking about new taphonomic models without show the evidences you have to support them? From which part of the bone bed you taken the samples? How the small, weathered fragments were distributed in the bone bed? You have to show that providing, as minimal requesting, a photograph that you will use to guide the readers into your analysis and final considerations. We need a photograph of the complete bone bed here, at least just one, to show the preservation type and spatial distribution of the fossils.

Why about time averaging? Do you think that all the carcases represented in the bone beds were deposited at the same time? Include the 46 Allosaurus skeletons individuals that can be considered juveniles? JP: The variability of abrasion of bone fragments suggests that not all exposed bones were destroyed at the same time. As such, we propose that the site is time averaged; carcasses were introduced over a period of time.

GP-How you arrive to such conclusion if you don´t provide images of the entire exposed bones? The isolated bones that you show in figure 3 are not enough proofs to make statements about the taphonomic history of more than 40 skeletons!

The majority of Allosaurus skeletons representing juveniles is not surprising; most extant archosaur populations are composed of mostly juvenile to subadult individuals. Finding a population of only old adults is quite rare.

GP- You mean crocodiles?, and you had into account that reptiles grow during all their lifes? Thus, here, the interesting will be that you explain how you would know about the real ontogenetic stage of the preserved 46 individuals.

The small fragments that you analyzed largely contrast with the good preservation of most of the bones preserved at the CLDQ and their origin is not clear from your manuscript. I did not understand why and how they were incorporate to the sediments at the same time with the complete and well preserved other bones. Might be the remains of “bones crushed by larger animals, such as sauropods, attempting to escape the miring mud”? By the way, you should include much better images to show the degree of abrasion of the intramatrix fragments and the inferred different stages as well. JP: Better IBF images have been revised and included. We are proposing that when carcasses were washed into the deposit and skeletonized, many remains would be buried. However, remains that were not buried would become destroyed and produce small fragments - perhaps from trampling or from increased aridity causing splintering of exposed remains. Crushing from animals attempting to escape from miring is unlikely due to the wide dispersal of bone fragments. In situ crushing would result in concentrated pockets of bone fragments, which is not seen in the quarry.

GP-And you saw the bones from where the fragments came on, fractured or incomplete? I am asking because I have no the reference in a clear-enough photograph.

I would like to see a photograph of the concretions that form nodules of calcite/barite around many of the bones from the CLDQ. JP: A photograph of a concreted bone has been added to Figure 7.
GP-It is not as clear as I would want, but maybe if you add some labels would be okay.

Concerning the unusual elevated amount of heavy metals and rare elements in the sediments and bones, do you considered the possibility that at least part of them were integrated to the soils recently? Several anthropogenic activities from modern days (mining, agriculture, fossil fuel exploration and exploitation, industries, etc) are extremely persisting contaminating of the environments and As, Cr, Ba, U, Zn, among others, were detected. This is just a suggestion for inquiring; maybe doing additional analyses, but it seems to be a repetitive problem in EDS analyses and other chemical studies of ancient sediments. JP: Further chemical analyses are planned for future work at the CLDQ and these helpful suggestions will be taken into consideration. It is doubtful that anthropogenic activities or recent activities are the origin of the metals seen in the quarry due to their isolated concentration in the bonebed and not elsewhere in the Morrison exposures in the area. Furthermore, the active excavations at CLDQ are taking place within buildings, whereas our other sample sites are exposed to air. If mining-related metals were being transported via air or rain, they would more likely accumulate outside of CLDQ than within.

GP-Not necessarily, because they might be there from before the bone bed was discovered. But, anyway, if you can prove that the rare elements are indeed syngenetic, you just have to try explain their origin, because sounds very uncommon that they were concentrated in such small area.

Other concerns are:

Fig. 5 is still very dark and out of focus. It needs to be improved.
Fig. 6 must be increased/improved in quality in the way that the reviewers and the editor can be able to see what you are describing in the text. So, please, improve your figuring; it is very poor to support the nice succession of taphonomic stages that you present in figure 9.

Version 0.1 (original submission)

· · Academic Editor

Minor Revisions

Dear authors,

I have three review reports about your manuscript and all reviewers consider it interesting for publication in PeerJ after Minor Revisions. I agree with all the comments and recommendations made by the reviewers and strongly support the concerns from Reviewer 1 in that your figures are poor and should be much improved. Besides, after read carefully your manuscript I have some comments and questions that require also to be revised:

-It could be very useful to your manuscript that you provide photographs of the quarries, showing a general view of the outcrops and also of the bone beds that you studied. Taphonomic studies require high quality and informative imaging to show what you are describing and interpreting, even more when you are suggesting a new taphonomic hypothesis.
-I could not see the phosphate crystallites from your figure 7.
-It could be also interesting that you can provide detailed images of the studied deposits and the compared bone beds.
-Why about time averaging? Do you think that all the carcases represented in the bone beds were deposited at the same time? Include the 46 Allosaurus skeletons individuals that can be considered juveniles?
-The small fragments that you analyzed largely contrast with the good preservation of most of the bones preserved at the CLDQ and their origin is not clear from your manuscript. I did not understand why and how they were incorporate to the sediments at the same time with the complete and well preserved other bones. Might be the remains of “bones crushed by larger animals, such as sauropods, attempting to escape the miring mud”? By the way, you should include much better images to show the degree of abrasion of the intramatrix fragments and the inferred different stages as well.
I would like to see a photograph of the concretions that form nodules of calcite/barite around many of the bones from the CLDQ.

-Concerning the unusual elevated amount of heavy metals and rare elements in the sediments and bones, do you considered the possibility that at least part of them were integrated to the soils recently? Several anthropogenic activities from modern days (mining, agriculture, fossil fuel exploration and exploitation, industries, etc) are extremely persisting contaminating of the environments and As, Cr, Ba, U, Zn, among others, were detected. This is just a suggestion for inquiring; maybe doing additional analyses, but it seems to be a repetitive problem in EDS analyses and other chemical studies of ancient sediments.

Please, consider all the constructive requests and comments about your manuscript made by the reviewers and from myself, because they will improve the quality and relevance of your work. Otherwise, provide a rebuttal letter explaining your argument to discard them.

Sincerely yours,
Graciela Piñeiro

·

Basic reporting

The authors' manuscript is generally well written in professional language and clear, though there are a suite of typos and grammatical errors that I have noted in my comments that can be quickly corrected. The authors consider only relevant literature and I had only a few very minor suggestions on a couple papers to briefly consider regarding their interpretations (of bone histology and taphonomic modifications). They provide a sufficient introduction and the manuscript is formatted consistently, save a few inconsistencies in the literature cited. The raw data are shared in the manuscript and its supplement. Figures are generally adequate, but Figures 5, 6, and 7 need improvement as follows. As noted in my general comments to the authors, the specimen images in Figure 5 are dark, blurry, and inconsistent with the abrasion categories they are assigned to. Every component of Figure 6 is too small, making the figure hard to read and understand. It could benefit from being reformatted into a different graph style, perhaps a spidergram. The photograph in Figure 7 appears washed out and the figure needs additional insets and images of other specimens in thin section for comparison and to support the assertion that highly abraded fragments are present in the assemblage.

Experimental design

The research is self contained and fits within the scope of PeerJ. The authors adequately describe their methods so that they could be replicated. These methods are appropriate for the questions at hand and are performed with reasonable rigor. The research question is clearly stated, meaningful, and relevant, and the analyses provide significant, meaningful additions to our knowledge of the taphonomic history of the Cleveland Lloyd Dinosaur Quarry. Though additional geochemical tests could be performed, they admittedly are beyond the scope of the authors current study; rather, they represent a potentially fruitful avenue of further research on the taphonomy of the sites studied.

Validity of the findings

The authors thoroughly discuss the many taphonomic scenarios suggested to account for the dinosaur assemblage at CLDQ, and draw conclusions within the limitations of their data and data from their references. This includes speculative scenarios, which are discussed as such and identified appropriately as possibilities to explain how the assemblage formed. Their data are generally sound, but I have questions concerning the interpretation of extensive abrasion to intramatrix bone fragments from CLDQ. As discussed in my general comments to the authors, based on the figures they present I am not convinced of the presence of well-rounded, highly abraded bone fragments at CLDQ. Though this may sound like a small issue, it has significant implications concerning the interpretation of sedimentary deposition processes and thereby depositional environments and the taphonomic history of the fossil assemblage - all of which are focused on in the manuscript. Based on what the authors state, they have access to sufficient fossil material to better address this issue.

Comments for the author

Dear Authors,

Please find copied below this section my point-by-point comments on your manuscript submitted to PeerJ. They are also available in the annotated PDF, but I felt it may also be useful to have them written in order.
I found your study of the chemistry and morphology of intramatrix bone fragments from the Cleveland Lloyd Dinosaur Quarry and studies of nearby quarries to provide an intriguing new look into the taphonomic history of this famous site and sites in the surrounding region. It certainly reinforces the importance of the maxim in taphonomy that one must study every last detail in order to best understand the history of a fossil assemblage. Your manuscript is generally well written and interpretations are framed within the limitations of the available, and as you note, somewhat conflicting data. The volume of sediment analyzed is adequate, and the number of IBFs characterized is sufficient in my view. Your discussion of possible explanations for the heightened concentrations of trace elements is intriguing, especially the consideration of bioaccumulation. However, I have a couple questions and a few suggestions to help improve the clarity of your manuscript and the conclusions you draw.
While I agree with your interpretations of depositional environments represented in the site stratigraphy in general, from what you present I would not find crevasse splay to be a plausible means of deposition at CLDQ. Absence of larger (non-fossil) grains in association with the IBFs and lack of hydraulic equivalency between the bones + IBFs and the enclosing sedimentary matrix grains are inconsistent with deposition of the strata by a single, relatively energetic event such as a crevasse splay. Unless there are other data not included in your manuscript that lend support towards relatively "high" energy deposition, it seems implausible to me for it to explain deposition at CLDQ.
More importantly, I am not convinced by the data you present that much, if any, of the IBFs from CLDQ are highly abraded/rounded. All of the IBFs figured, including the specimen in Figure 7, appear angular to subangular to me. The images in Figure 5 are oddly dark (please increase their brightness and sharpness) and appear rough, with pointed corners, many protrusions, and sharp ridges inconsistent with increasing abrasive roundedness at higher stages. These features inconsistent with rounding mean that the images for the abrasion categories must be replaced, assuming IBFs assignable to each category are truly present in your assemblage. My question then is do you have more convincing evidence of extensive abrasion/rounding of IBFs from the site? And if so, how might you suggest this rounding occurred when there appears to be no evidence for high energy transportation and deposition?
There also appears to potentially be concretion coatings and/or sediment adhered to the IBFs in the images in Figure 5, obscuring the true bone fragment surfaces. This reinforces the need for better images, and hopefully of "better" specimens. If concretion/mineral coatings are indeed an issue, histology may be a helpful assay for determining if any IBFs are well rounded. If a well-rounded IBF is present, please insert a figure of it in thin section in your Figure 7. On a related note, I could find no discussion of the range of histologic integrity of IBFs from CLDQ: this information should be provided, perhaps with scoring on the HI scale of Hedges and Millard (1995).
If, upon further consideration, you no longer feel that well-rounded IBFs are present at CLDQ, then it may actually help simplify some of your interpretations. Absence of significant abrasive rounding would imply an absence of allochthonous material and potentially eliminate any attritional component to the assemblage. Such a conclusion would also be consistent with the limited taxonomic representation at the quarry of smaller organisms (which is again inconsistent with deposition by a crevasse splay sweeping across the floodplain).
A few additional comments on figures: I feel Figure 7 should also include an inset zoom in on the bone microstructure of an IBF and the microstructure of an adjacent secondary apatite crystallite. I could not tell where one ends and the other begins in your current image. Perhaps a small arrow at the boundary could help too? Figure 6 should at least be drastically increased in size in all aspects, if not instead reformatted (i.e., vertical bar graphs, concentration spidergram) or broken up into a few separate graphs. It is currently tiny in all aspects.
I agree with your conclusion closing the Discussion that further geochemical testing could help potentially be very helpful in resolving many of the remaining unknowns in your site's history. In particular, though it is likely beyond the scope of your current study, analyses of rare earth element (REE) compositions of bones and IBFs by laser ablation-ICPMS have the potential to diagnose the presence of any allochthonous fossils. REE concentration absolute values, spatial distributions, and variation among fossils could indeed answer whether or not bones were brought in from across the landscape (unless late diagenetic overprinting occurred).
Although I have other comments as well, most relate to the few topics outlined above or are quick, small writing changes to aid clarity. Again, your manuscript is intriguing and sheds important light on an aspect of the taphonomy of the site previously overlooked. I am more than happy to help direct you to any reference I have noted as needed. I would be happy to take a second look after your revisions if the editor feels fit to send it my way, and can answer any questions via email at: ullmann@rowan.edu.

With best regards,

Paul V. Ullmann

References noted:
Behrensmeyer, AK, Gordon, KD, and Yanagi GT. 1986. Trampling as a cause of bone surface damage and pseudo-cutmarks. Nature 319:768-771.

Hedges, REM, and Millard, AR. 1995. Measurements and relationships of diagenetic alteration of bone from three archaeological sites. Journal of Archaeological Science 22:201-209.

Kohn, MJ, and Moses RJ. 2013. Trace element diffusivities in bone rule out simple diffusive uptake during fossilization but explain in vivo uptake and release. Proceedings of the National Academy of Sciences 110:419-424.

Trueman, CN. 1999. Rare earth element geochemistry and taphonomy of terrestrial vertebrate assemblages. PALAIOS 14:555-568.

Point By Point Comments:
Page 7 line 46: maybe reword? Sounds odd to have "elevated REE" as even a potential "driver for the accumulation of carcasses". Is this suggesting some kind of environmental toxicity as a killing agent?
Page 8 line 48: and what is that specific depositional environment? Please be more specific for the abstract.
Page 8 line 49: in this region.
Page 9 line 60: can you please be more specific here as to what you mean by "Jurassic paleoecological data"? Is this, for example, referring to (potentially) predator behavior?
Page 10 line 76: don't know if this is journal specific, but most require commas after e.g. and i.e. Also, most require use of an en-dash for numbers series or dates rather than a hyphen (may need to fix in paragraph above, for example).
Page 10 line 77: remove the word "and".
Page 11 line 106: you are inconsistent in the use of commas after authors in your citations through the text. Should consistently use commas.
Page 11 line 110: use suggested instead of suggests.
Page 11 line 116: this sentence does not make sense. Is it intended to say "mire" instead of "predator trap" at the start?
Page 11 line 118: By pit wear, are you referring to so-called "trampling marks" as described by Behrensmeyer et al. 1986?
Page 12 line 138: in an attempt. Add the word "an".
Page 13 line 158: capitalize Late.
page 14 line 181: agreed.
Page 17 line 250: yes, this does seem like an adequate volume for characterization.
Page 18 line 271: maybe type this equation section in manually so the text font and line spacing match the rest of the text.
Page 18 line 275: fragments not fragment.
Page 19 line 286: in not on. Also, sentences merely stating data are in table # are generally superfluous.
Page 19 line 287: Perhaps say "Two analyzed strata, Units 1b and 25, also contained..." This would make it clearer.
Page 19 line 290: any thoughts on the source(s) for the copper and lead?
Page 19 line 292: same comment as for first sentence of previous paragraph, including the change of "on" to "in".
Page 19 line 294: same comment as previous.
Page 19 line 297: capitalize Members.
Page 19 line 304: by "CLDQ sediment" are you referring to the bone-bearing horizon at CLDQ?
Page 20 line 324: should include at least a brief discussion about the histologic integrity of the sectioned specimens. Also, how many sections were made? Do not see mention of this anywhere.
Page 21 line 334: reword for clarity please. Something like "IBFs exhibit a continuum in degrees of abrasion, with all categories (0-3) represented by 15 to 30% of the remains."
Page 21 line 354: If the dinosaur carcasses were accruing on a multi-generational attritional scale, then there may not have been a short term "abundance of decaying dinosaurs" at any time point. Is something to consider. Also, "the abundance of decaying dinosaurs utilizing" is odd phrasing. Perhaps "High levels of decaying organic matter, possibly including a short-term abundance of decaying dinosaurs, may have lead to depletion of dissolved oxygen, thereby contributing to reducing conditions."
Page 22 line 359: Seems to me this should be worded more like "and these tissues would likely constitute the most abundant sources of organic matter during the late stages of decay."
Page 22 line 362: Can you provide an image of one as an example? Also might be beneficial to quickly get some counts on concretion locations to back up this assertion with a percentage.
Page 22 line 369: explanation for, not explanation of.
Page 23 line 379: While this is true, abundance of U merely indicates the bones were interacting with groundwater at some point during diagenesis. Though uptake likely occurred early in diagenesis (given the efficiency of bone as a trace element sink - see Kohn & Moses 2013), your U data do not lean towards a pond over other depositional environments with high water tables, e.g., fluvial channel, wet floodplain. Therefore you can only state that the U data support burial taking place in a, well, 'moist' environment, which could include an ephemeral pond as an option.
Page 24 line 401: are you referring to the bone or sediment from MMQ, or both?
Page 24 line 404: interesting.
Page 25 line 427: agreed.
Page 25 line 439: should include page number in the citation if directly citing them in quotes.
Page 26 line 448: insert the word "of" after source.
Page 26 line 449: Likely feels a little strong for me. Perhaps something more like "appears to derive at least in part from the decay..."
Page 26 line 452: place these taxa in parentheses instead of using e.g. in line in the sentence.
Page 26 line 455: see previous comment.
Page 26 line 456: Use "a hypereutrophic water column" instead to be more clear.
Page 26 line 457: This inference needs a citation.
Page 26 line 466: strengthens not strengthen.
Page 26 line 467: Should end the sentence with "within the Morrison Formation."
Page 26 line 467: see comment above about the use of e.g. within sentences.
Page 27 line 469: Data is plural not singular, so you should say "These data support the hypothesis..."
Page 27 line 470: contributor of rather than contributor to.
Page 27 line 472: Here is confusing. Suggest replacing with "at JONS" or "there" instead.
Page 27 line 473: I do not follow this statement, unless you are referring to the organic remains as the primary source of the metals at each site. If this is the intended assertion, please make the sentence more clear to refer to bioaccumulation.
Page 28 line 496: Their results rather than The results.
Page 28 line 500: capitalize Upper.
Page 28 line 502: Suggest stating the p value here again at the end of the sentence in parentheses.
Page 28 line 503: corresponded to rather than corresponded with.
Page 28 line 512: Given you are talking about particles, I'd suggest taking out the (inadvertently) misleading "particular" here.
Page 29 line 514: are likely a mixture (insert the word likely).
Page 29 line 514: given the redundancy of "locally-crushed" here, take out the first use of it.
Page 29 line 516: Considering the absence of larger grains (sand) within your entombing matrices at both sites, crevasse splay seems unlikely to me, especially given the absence of hydraulic equivalency evidence for simultaneous deposition of the mudstone and larger fossil fragments. For such an event to bring in allochthonous fossils, you would also expect to see allochthonous sand grains to be brought in, and you do not apparently see that at either site. Unless I am missing or unaware of another sedimentologic or stratigraphic detail (e.g., primary sedimentary structures) that suggest crevasse splay deposition, it seems implausible. This conclusion also makes "allochthonous fragments" implausible, given the data you've presented.
Page 29 line 524: For clarity, change the wording here to "interpretation of deposition occurring by a crevasse splay in an environment with a generally high water table, likely a wet floodplain (Bilbey, 1998)."
Page 29 line 527: Change to "degree of abrasion of IBFs, with..."
Page 29 line 528: Not sure what you mean here by "normally". Do you mean usually, or predominately?
Page 29 line 531: See my comment on Figure 5 for my thoughts on potential allochthonous IBFs at CLDQ.
Page 29 line 531: italicize sensu.
Page 31 line 560: italicize sensu.
Page 31 line 565: add "in this region" after Late Jurassic.
Page 31 line 578: insert the word "of" after result.
Page 32 line 583: based on my comments above, if only a very few specimens are allochthonous or highly abraded, then the attritional component would be quite minimal.
Page 33 line 607: replace italicized semicolon with a non-italicized comma.
Page 33 line 608: Is the histologic microstructure of the eggshell consistent with ootaxa attributed to theropods? And if the egg was complete enough, was its shape also elongate (again, consistent with others attributed to or known with certainty to be made by theropods)? If these answers are known, they should be included. If not, that should also be stated.
Page 33 line 620: Agreed. I have found analyses of the rare earth element composition of fossil bones via laser ablation ICPMS to be a very effective way of investigating these type of questions. For example, if compositional patterns were found to be relatively homogenous and low in concentrations (i.e., only 10's ppm in most of the cortex), it would suggest general retention of early diagenetic trace element signatures that varied little, thus implying a lack of allochthonous/attritional input into the assemblage. In contrast, if varied trace element signatures were found that cannot reasonably be explained by differences in bone tissue structure alone, it would lend support to the inclusion of bones from "across the landscape" as you state. Of course, late diagenetic overprinting could always obscure either trend though.
Page 33 line 626: As you did not assess weathering stage in the traditional Behrensmeyer sense, be a little careful in how you describe what you assessed. In other words, stating that weathering was assessed would lead me to think of the Behrensmeyer stages...
Page 33 line 627: replace "and" with "an".
Page 34 line 640: There could be other, non-organically driven means of inorganically precipitating calcite nodules, correct? Like caliche in paleosols. I know you note that there is negligible signs of paleosol development, but just pointing out that calcareous soaps are not "required" to form calcite nodules in sedimentary deposits.
Page 35 line 655: make "suggests" singular (suggest).
Page 37 line 702: make the "and" in normal font rather than small caps.
Page 37 line 726: fix the "and" as above.
Page 39 line 794: fix the "and" as above.
Page 39 line 798: fix the "and" as above.
Page 39 line 798: uncapitalize vertisol.
Page 39 line 824: fix the "and" as above.
Page 40 line 831: fix the "and" as above.
Page 40 line 835: extra line here.
Page 40 line 836: fix the "and" here and in the next 4 refs.
Page 40 line 849: The format for citing articles within books is inconsistent here. Compare your formatting of Rees et al. 2000 to that of Richmond and Morris 1996.
Page 40 line 849: fix the "and".
Page 40 line 860: fix the "and".
Page 40 line 867: italicize Caiman crocodilus crocodilus.
Page 41 line 884: sometimes you are putting a period after the year and other times you are putting a comma. Make consistent.
Page 41 line 896: fix the "and".
Page 48, Figure 3: Is this the most detailed taxonomic assignment of all these materials?
Page 50, Figure 5: the images here are all quite dark. I'd suggest lightening them if possible. They also seem slightly blurry. Lastly, it is difficult at least for me to see any difference between the fragment assigned as "subangular" vs the one assigned as "subrounded". Perhaps there are better fragments to illustrate the scale?
Page 50, Figure 5: after inspecting this image for an extended period of time, I am not convinced that this fragment is particularly rounded. Abrasive rounding imparts smoothness to corners, which is not what I'm seeing here. Rather, all of the presented fragments appear to present distinct ridges, decently sharp corners, small protrusions, and very rough surfaces. Multiple of the fragments shown appear to maybe have diagenetic mineral crystal coatings at least over parts of them, and/or concretions coating surfaces that may partially fill vascular cavities and obscure the bone fragments' true surfaces. Is this true? Overall, the shape inconsistencies I stated above force me to seriously question the presence of alllochthonous IBFs at CLDQ. The histologic image in Figure 7 also portrays rather sharp corners and rough edges, again inconsistent with extensive abrasion. High resolution thin section images could be one means of telling weather an IBF has undergone significant abrasion, as it could show smooth, even truncation of bone histologic features (e.g., secondary osteons). If the authors feels they have an image of an IBF displaying extensive rounding/abrasion, it should be included in Figure 7 as (visual) support for their conclusion. Given the current images, I am not convinced.
Page 51, Figure 6 caption: insert the word "from" after "sediments".
Page 51, Figure 6: This entire image is tiny. Please enlarge every aspect, including the text, axis labels, and concentration bars. This may require splitting the image into multiple pieces or rearranging the data into either vertical bar graphs or concentration spidergrams (in the way REE data for fossil bones are often presented - see Trueman et al. 1999 for an example).
Page 52, Figure 7: Image appears a bit washed out. Also, the apparently complete degradation of original histologic structure deserves to be mentioned. Third, you should provide a zoom in on a single one of these crystallite pockets and the surrounding bone histology, allowing detailed comparison of their microstructures - I am having real trouble telling where the bone fragment ends and the secondary apatite crystals begin... Is the majority of this "fragment" infilling crystallites rather than original bone?
Page 54, Figure 9 caption: Can you add a parentheses with examples at the end of this sentence of biostratinomic processes you are referring to? (e.g., _, _). I presume scavenging is one of them?
Page 54, Figure 9: How do you suggest the physical abrasion is occurring essentially without transport? This statement still begs for an explanation.
Page 58, Table 2 caption: part D would be much clearer if the caption stated "number of IBFs assigned to each abrasion stage of Wilson (2008)".
Page 59, Table 2: Perhaps Inferred Depositional Environment instead of Interpretation.
Page 59, Table 2: the p value is not needed in this table. It is stated clearly in the text, which I feel to be sufficient enough to remove it here.
Page 59, Table 2: what are the units for the average hydraulic equivalent? Millimeters? And the units for relative densities? Grams/cubic centimeter? State these in the caption or table please.
Page 61, Table 3: are these ranges in concentrations? If so, are they in ppm? This was not stated in the table caption nor the main text.

·

Basic reporting

Overall, the basic reporting is sound. I offer a few small edits:

Paytan and Griffith, 2007 on line 364 appears to be missing in works cited.

Hare E.P, 1974 on line 774 should be Amino not Animo?

Sellwood B. W...... line 860, the year is incomplete (200) but cited as 2008 in text on line 556

Morrison Formation should be capitalized. Also, I believe it is best if the word formation always follow the word Morrison since it is the formation that is being discussed. This is inconsistent throughout the text. For example the word formation is not capitalized on line 374 and then becomes absent on lines 449 and 600.

On line 494 the sentence starts with Peterson et al. (2011) and then is cited again at the end of the sentence. I do not think the second citing is needed.

Experimental design

no comment

Validity of the findings

no comment

Comments for the author

A few minor comments:
on line 57, it would help if MNI was defined. Also, in sampling, was the left femoral used in all taxa or just Allosaurus fragilis (in italics)? In Figure 2 it would be nice to see the total count so that we know what the percentages represent.

For historical reasons, I would add the dates the samples were collected to go along with the BLM permits on lines 207 and 208.

In the document, the citing starting on line 780 appears to be a lighter shade. It is not clear as to why.

·

Basic reporting

Overall the paper looks good regarding Basic Reporting. See my comments in the appended file for grammar.

Experimental design

All looks good. No Comment.

Validity of the findings

My only comment in regard to Validity is that I am not totally convinced that the resulting data from the analyses in this paper support the idea of dinosaur carcasses were transported to CLDQ. I would recommend stating these conclusions as more speculative.

Comments for the author

This paper is a great contribution to the study of the CLDQ. Please see the appended document for specific comments throughout the paper. I urge the authors to make their interpretation of carcass transportation to the site clearer as speculation, or one of two ideas that can explain the data. I am not convinced of this point given your data. Also, I feel that you do not give enough flexibility in varous places in the paper to account for the information that we probably will never know regarding paleotopography, dinosaur behavior, etc. These points are mentioned in the marked paper. Everything else you present seems solid.

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