New records of theropods from the latest Cretaceous of New Jersey and the Maastrichtian Appalachian fauna

The faunal changes that occurred in the few million years before the Cretaceous–Palaeogene extinction are of much interest to vertebrate palaeontologists. Western North America preserves arguably the best fossil record from this time, whereas terrestrial vertebrate fossils from the eastern portion of the continent are usually limited to isolated, eroded postcranial remains. Examination of fragmentary specimens from the American east, which was isolated for the majority of the Cretaceous as the landmass Appalachia, is nonetheless important for better understanding dinosaur diversity at the end of the Mesozoic. Here, I report on two theropod teeth from the Mount Laurel Formation, a lower-middle Maastrichtian unit from northeastern North America. One of these preserves in detail the structure of the outer enamel and resembles the dentition of the tyrannosauroid Dryptosaurus aquilunguis among latest Cretaceous forms in being heavily mediolaterally compressed and showing many moderately developed enamel crenulations. Along with previously reported tyrannosauroid material from the Mt Laurel and overlying Cretaceous units, this fossil supports the presence of non-tyrannosaurid tyrannosauroids in the Campanian–Maastrichtian of eastern North America and provides evidence for the hypothesis that the area was still home to relictual vertebrates through the end of the Mesozoic. The other tooth is assignable to a dromaeosaurid and represents both the youngest occurrence of a non-avian maniraptoran in eastern North America and the first from the Maastrichtian reported east of the Mississippi. This tooth, which belonged to a 3–4 m dromaeosaurid based on size comparisons with the teeth of taxa for which skeletons are known, increases the diversity of the Maastrichtian dinosaur fauna of Appalachia. Along with previously reported dromaeosaurid teeth, the Mt Laurel specimen supports the presence of mid-sized to large dromaeosaurids in eastern North America throughout the Cretaceous.

Further the author suggests ways that these teeth contribute to our knowledge of faunal interchange between eastern and western North America at the Campano-Maastrichtian boundary.
This paper is important for the acknowledgement of the taxa found in this New Jersey formation. Outside of this finding there is much more difficulty in acquiring significance. This problem of lack of greater significance is not the fault of the author but the nature of the Appalachian dinosaur record. Fossiliferous formations are poorly dated, fossils are not terribly abundant, and when known are typically in rough condition. Because there is not a proper framework for the dinosaurs, determining faunal interchange is problematic...you need to know what is around when, and the organism's phylogenetic relationships. Without this it is difficult to say anything concrete about paleobiology. Especially, in these days when doing rigorous biogeographic analyses is so easy. In my opinion you can't really say anything about faunal interchange until a solid, dated fossil record is assembled.
I am glad to see the author using quantitative techniques to identify the teeth. However, I have some issues with the methods and/or the results presented. First, I firmly do not think that a phylogenetic analysis should be used on a single tooth, much less a single partial tooth. The phylogenetic analysis of teeth is not a proper use of phylogenetics in my opinion at any rate. To my mind this part of the paper should be eliminated.
Second, the author should use a more recent ordinal analysis of teeth. This is not a deal breaker, but the primary dataset chosen is 13 years old (or 5 yrs old in the case of Larson and Currie) and many others have been produced since then.
Third, the tyrannosaur tooth should absolutely be removed from the PCA analysis. It is a fragmentary tooth, therefore any measurements taken are not going to be the correct measurement and will provide erroneous results. Or there will be too little data to say much about.
Fourth, the dromaeosaurid tooth falls outside the dromaeosaurids in the Smith/Brownstein matrix. And is just part of the miasma of teeth in the Larson and Currie matrix. I would suggest pulling individual taxa from the analyses and talk about comparisons with them instead of consistently saying it is a Saurornithlestesine theropod. Remember that the PCA is using data you input. If there is more information supporting your taxonomic claim that is not included in the quantitative data, then you should discuss this in the text. In PAST you can change the symbol and the color, meaning that you can label individual dinosaur taxa and the higher level taxonomic groups at the same time. This should be done to help you see which species the Tar Heel and Mt Laurel specimens are mostly similar to.
Fifth, this is very important! When using PCA on variables that are measurements, the first axis is almost invariably a reflection of size, not shape. Therefore, you need to show axes 2 and 3. You are welcome to retain axis 1 and 2, but 2 and 3 must be shown in addition. You may also want to consider Centering or z-transforming your data because it can help remove the effect of size, bring outliers closer together, and reflect shape better.
I have provided a marked PDF with more comments and suggestions (Appendix A).
Hopefully these suggestions help the paper and the author. Manuscript ID RSOS-190533 entitled "New records of theropods from New Jersey inform faunal interchange in Maastrichtian North America" which you submitted to Royal Society Open Science, has been reviewed. The comments from reviewers are included at the bottom of this letter.
In view of the criticisms of the reviewers, the manuscript has been rejected in its current form. However, a new manuscript may be submitted which takes into consideration these comments.
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Once you have revised your manuscript, go to https://mc.manuscriptcentral.com/rsos and login to your Author Center. Click on "Manuscripts with Decisions," and then click on "Create a specimens towards the tyrannosaur part of your plot (as there are more tyrannosaurs in the dataset than any other group). Given that all three of the new teeth plot in areas of your plots where no other theropod teeth plot (partway between dromaesaurs and tyrannosaurs), it appears that column average substitution of your dataset is having a substantial contribution to the position of your specimens on these plots. As well, eastern taxa are notably excluded. Dryptosaurus is not plotted in Fig. 2A, and the Tar Heel dromaeosaurid is not plotted in Fig. 4B and 4C, making the argument that either of these teeth have eastern or western affinities insufficiently supported by these analyses. Additions of those specimens and the exclusion of variables with missing data are necessary for these plots to be informative.
In the phylogenetic analysis, you only list shared derived characters between your tyrannosaur specimen and T. rex, but do not list shared derived characters that unite all tyrannosauroids. However, even this analysis does not support your argument that the specimen is a nontyrannosaurid tyrannosauroid with affinities with Dryptosaurus. Also, one of the four characters you do list, 94) biconvex apical distal denticles, is not mentioned in your description at all nor is it visible in Fig. 1. As well, Fig. 1B, 1C, and 1D depict fossils that are not described in the manuscript. If these specimens are figured in this manuscript, they should be described systematically in the text. Alternatively, these figures could easily be excluded from the manuscript. The entire datasets used for analysis, including the  and  should be reproduced in the supplemental data for ease of replication.
This description is of specialist interest given the new records from eastern North America, but any discussion of faunal interchange in premature. In your description, you have demonstrated that you have teeth of a dromaeosaurid and a tyrannosauroid from this formation, but your analyses in their current form are insufficient to demonstrate that these teeth have any biogeographic affinities.

Reviewer: 2
Comments to the Author(s) The author of this paper has identified two theropod dinosaur teeth from the east coast of North America they attribute to Tyrannosauroidea and Dromaeosauridae.
Further the author suggests ways that these teeth contribute to our knowledge of faunal interchange between eastern and western North America at the Campano-Maastrichtian boundary.
This paper is important for the acknowledgement of the taxa found in this New Jersey formation. Outside of this finding there is much more difficulty in acquiring significance. This problem of lack of greater significance is not the fault of the author but the nature of the Appalachian dinosaur record. Fossiliferous formations are poorly dated, fossils are not terribly abundant, and when known are typically in rough condition. Because there is not a proper framework for the dinosaurs, determining faunal interchange is problematic...you need to know what is around when, and the organism's phylogenetic relationships. Without this it is difficult to say anything concrete about paleobiology. Especially, in these days when doing rigorous biogeographic analyses is so easy. In my opinion you can't really say anything about faunal interchange until a solid, dated fossil record is assembled.
I am glad to see the author using quantitative techniques to identify the teeth. However, I have some issues with the methods and/or the results presented.
First, I firmly do not think that a phylogenetic analysis should be used on a single tooth, much less a single partial tooth. The phylogenetic analysis of teeth is not a proper use of phylogenetics in my opinion at any rate. To my mind this part of the paper should be eliminated.
Second, the author should use a more recent ordinal analysis of teeth. This is not a deal breaker, but the primary dataset chosen is 13 years old (or 5 yrs old in the case of Larson and Currie) and many others have been produced since then.
Third, the tyrannosaur tooth should absolutely be removed from the PCA analysis. It is a fragmentary tooth, therefore any measurements taken are not going to be the correct measurement and will provide erroneous results. Or there will be too little data to say much about.
Fourth, the dromaeosaurid tooth falls outside the dromaeosaurids in the Smith/Brownstein matrix. And is just part of the miasma of teeth in the Larson and Currie matrix. I would suggest pulling individual taxa from the analyses and talk about comparisons with them instead of consistently saying it is a Saurornithlestesine theropod. Remember that the PCA is using data you input. If there is more information supporting your taxonomic claim that is not included in the quantitative data, then you should discuss this in the text. In PAST you can change the symbol and the color, meaning that you can label individual dinosaur taxa and the higher level taxonomic groups at the same time. This should be done to help you see which species the Tar Heel and Mt Laurel specimens are mostly similar to.
Fifth, this is very important! When using PCA on variables that are measurements, the first axis is almost invariably a reflection of size, not shape. Therefore, you need to show axes 2 and 3. You are welcome to retain axis 1 and 2, but 2 and 3 must be shown in addition. You may also want to consider Centering or z-transforming your data because it can help remove the effect of size, bring outliers closer together, and reflect shape better.

Methods
Page 25, line 406: change "provide support for the assignment" to "quantitatively test the identity". Page 26, line 429: change "provide additional support for" to "test". On behalf of the Editor, I am pleased to inform you that your Manuscript RSOS-191206 entitled "New records of theropods from New Jersey inform faunal interchange in Maastrichtian North America" has been accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the referees' comments at the end of this email.
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Reviewer comments to Author: Reviewer: 2 Comments to the Author(s) The paper is much improved since I last reviewed it. There are comments posted in another annotated pdf attached to this review. Important changes that still need to be made. First and foremost--the phylogenetic analysis of teeth. You must use the super matrix of Hendrickx and Mateo, not just the tooth matrix. Please recode and rerun the analysis. Also, you should add Dryptosaurus and potentially one other tyrannosaurid to the matrix so that you might get some resolution as to the phylogenetic affinities of your tooth. Without this there is little that can be said except it is a tyrannosauroid tooth.
Put some or all of the Discriminant Analysis results in the paper, not the SM. We need to see the data.
The last sentence of the abstract does not make sense. I suggest deleting it, but you can try to modify it.
Good luck with further revisions.

Terry Gates
Reviewer: 3 Comments to the Author(s) This revision of the original paper is much better present and the interpretations are supported. I think it is nearly ready for publication. I made minor corrections to the MS on the PDF. Please be careful with the use of the clade names. Tyrannosaurids = members of Tyrannosauridae. I noted these throughout. Also, put the description before the identification of each tooth section.

Reviewer: 4
Comments to the Author(s) Dear Editor, I submit to you my review of MS RSOS-191206, "New records of theropods from New Jersey inform faunal interchange in Maastrichtian North America" by Brownstein. This article is a longoverdue consideration of the possibility of faunal exchange between Laramidia and Appalachia during the latest Cretaceous. Virtually all paleogeographic maps of this time show Laramidia and Appalachia joined across what is now western Canada, where previously they were decisively separated by the Western Interior Seaway (WIS). However, the complete absence of Appalachian dinosaurs from the Hell Creek Formation and its equivalents sets the null hypothesis that faunal exchange, at least from east to west, did not occur. In his manuscript, Brownstein compares these hypotheses from the perspective of the east.
If dispersal went in the opposite direction (west to east), then fossils of, say, Tyrannosaurus rex and Triceratops should be present in late Maastrichtian sedimentary rocks of Appalachia. Indeed, if T. rex did disperse from Central Asia to Laramidia, becoming nearly instantaneously widespread across that landmass, then Appalachia should have been occupied in the same fashion. But that isn't what the fossil record shows: certainly, opportunity for faunal exchange presented itself at 76, 74, and 68 million years ago, but there is no evidence of it in Laramidia, and the basal nature of Appalachiosaurus (Campanian) and Dryptosaurus (Maastrichtian) are consistent with that pattern. In the end, the author does conclude that the tooth specimens that he describes provide evidence for the refugium hypothesis, a conclusion that I agree with. I suggest publication with minor revision; in addition to the specific comments below, I think the author should more clearly couch the article in terms of the refugium versus exchange models. In the introduction and conclusion, he leans heavily on the exchange model and that needs to be balanced, in both places, by a skeptical assessment of the case for the exchange model. An explicit statement of the evidence in favor of the refugium hypothesis must also be included in the abstract and the title must be adjusted accordingly.

22-Oct-2019
Dear Mr Brownstein, I am pleased to inform you that your manuscript entitled "New records of theropods from the latest Cretaceous of New Jersey and the Maastrichtian Appalachian fauna" is now accepted for publication in Royal Society Open Science.
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The faunal changes that occurred in the few million years before the Cretaceous-Paleogene extinction are of much interest to vertebrate paleontologists. Western North America preserves arguably the best fossil record from this time, whereas terrestrial vertebrate fossils from the eastern portion of the continent are usually limited to isolated, eroded postcranial remains. Here, I report on two theropod teeth from the Mount Laurel Formation, a lower-middle Maastrichtian unit from northeastern North America. One of these preserves in fine-detail the structure of the outer enamel and closely resembles the dentition of the tyrannosauroid Dryptosaurus aquilunguis. The other is assignable to a dromaeosaurid and represents both the youngest occurrence of a non-avian maniraptoran in eastern North America and the first from the Maastrichtian reported east of the Mississippi. Unlike other dromaeosaurid teeth from the northeastern portion of the continent, the Mt. Laurel specimen is closely comparable with western North American ones. Taken together, these fossils suggest a complex biogeography for dinosaurs in the American east. Although the tyrannosauroid tooth provides an additional record of non-tyrannosaurid tyrannosauroids in the Maastrichtian of eastern North America, the dromaeosaurid specimen indicates faunal interchange between eastern and western North America began to take place as early as the early Maastrichtian, several million years earlier than previous discoveries indicated. Along 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60 Introduction.
The extinction of the non-avian dinosaurs at the end of the Mesozoic Era is a topic that has continued to intrigue vertebrate paleontologists (e.g.,   , and ornithomimosaurs .
Despite the amount of knowledge of Cretaceous faunal change to be gleaned from the fossil record of Appalachia, the assemblages of this landmass have remained fundamentally understudied since the mid-19th century (e.g., . The scarcity of terrestrial sedimentary units known from the eastern half of the United States has also contributed to the obscurity of Appalachian faunas compared to western North American ones  ;  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59   , although some, such as the Woodbury and New Egypt formations, are notable for producing some of the first partial dinosaur skeletons from the Americas (e.g., Gallagher, 1993, Weishampel and. One of the most fossiliferous of these formations is the Mount Laurel Formation, which is either uppermost Campanian or lowermost Maastrichtian  and in New Jersey has produced the remains of several groups of dinosaurs, including hadrosaurs, tyrannosaurs, and ornithomimosaurs . Because of the sheer diversity of the community represented in the Mt. Laurel, the formation serves as a window into Maastrichtian eastern North American faunas. However, the terrestrial fossils it produces are often eroded postcranial fragments .
Here, I describe some theropod teeth from the Mt. Laurel Formation of New Jersey.
These include a large tooth assignable to a mid-sized (est. 6-8 m) tyrannosauroid and a smaller, heavily recurved one assignable to a smallish (est.

Results.
Geological setting. Both theropod teeth described here were collected from sediments of the Mount Laurel Formation ; pers. obs.), a marine deposit that represents a regression of the Atlantic Ocean during the Late Cretaceous period and is the oldest unit included in the Monmouth Group ). The tyrannosauroid tooth described here, NJSM GP 12456, was recovered from Big Brook (Fig. 1A), a highly fossiliferous locality famous for producing an extensive marine fauna . At Big Brook, the stratigraphic column is exposed along the banks, with the Mt. Laurel smoothly transitioning from the underlying Wenonah Formation such that the border between the two are indistinguishable . The contact between the Mt. Laurel and the overlying Navesink Formation is highly irregular . The Mt. Laurel Formation appears as gray to dark brown, pebbly quartz sands. The Big Brook tyrannosauroid tooth (Fig. 1E-H) is unusual among the terrestrial vertebrate teeth collected from the site in possessing a well-preserved enamel surface. Whereas other terrestrial vertebrate fossils from Big Brook are known for being heavily water-worn and lacking morphological details, NJSM GP 12456 preserves both its outermost enamel layer and many of its denticles.
NJSM GP 22949, the dromaeosaurid tooth, was recovered from Mt. Laurel deposits in Burlington County, New Jersey (Fig. 1A). In this area, which makes up a portion of the southwestern-most range of the Monmouth Group, the sands of the Mt. Laurel are more glauconitic than farther north and are intermixed with iron compounds . The thickness of this unit is also far greater to the southwest of its range (e.g.,    . In addition to its size, the Mt. Laurel tooth resembles those of tyrannosaurs among theropods known from Late Cretaceous North America in possessing packed denticles (2-2.5/mm) on its distal carina (15+ mm), the presence of denticles along both carinae, the straightness of its distal margin, the presence of numerous transverse undulations (density = 2/mm) on its main surface, and its smooth but irregular surface texture ( Fig 1E-H  These are characters 94 (biconvex apical denticles present on distal carinae of lateral teeth), 100 (subequal number of denticles apically than at mid-crown portion of distal carinae on lateral teeth), 103 (interdenticular space between mid-crown denticles on distal carinae of lateral teeth broad), and 105 (interdenticular sulci between mid-crown denticles on distal carinae of lateral  NJSM GP 14256 (Fig. 1) is the apical half of the tooth of a theropod dinosaur.
Measurements of the specimen may be found in Table 1. The tooth is well-preserved for a terrestrial fossil collected from one of the marine deposits of the Cretaceous Atlantic Coastal Plain, preserving details of the outer enamel layer and denticle morphology. Unfortunately, the basal half of the crown and the entirety of the root of the tooth are not preserved. This is probably due to erosion, as the tooth is broken transversely and heavily rounded at its preserved base ( Fig. 1E-F).
The tooth displays the ziphodont condition in being labiolingually compressed and only slightly recurved. The preserved mesial carina is slightly convex, whereas the distal carina is straightened along its entire run. The labial and lingual portions of the enamel are well-preserved  2015a). The apex of the tooth bears a slight wear facet on its lingual surface. The tooth is lenticular in basal cross-section.
The distal carina preserves many denticles ( Fig. 1E-F, H), which are small, dense (6/ mm), and apicobasally straightened. The denticles are and are interspersed with diminutive interdenticular sulci (the "blood grooves" of ). These are encompassed by the apical ends of the denticles. These denticles maintain a similar density along Identification.
In distal view, the middle portion of tooth is convex labially and distally, although the crown becomes labiolingually straightened towards its apex. The labial and lingual surfaces are flattened, and the lack of a root attached to this crown indicates it was shed. Although both the 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60 mesial and distal carinae are preserved, the mesial denticles have been eroded away. Some portions of the tooth crown are cracked, and the outer enamel layer is poorly preserved towards the distal end of the specimen. Small portions of the middle of the crown are missing. The distal profile of NJSM GP 22949 is strongly concave and more developed in basal cross-section than the mesial. The preserved portions of the outer enamel layer are smooth, although at the apex several slightly developed ridges appear. These ridges could represent features of the original morphology of the tooth or be damage from feeding or taphonomic processes.
The distal carina preserves a large number of apically hooked denticles that become smaller towards the apex of the crown. These denticles are separated by interdenticular sulci that, along with the serrations, project slightly onto the tooth surface. Unfortunately, the shape and density of the mesial denticles could not be determined, as the mesial carina is heavily eroded in NJSM GP 22949.

Conclusions.
Two

Methods.
Measurements and nomenclature.
To provide additional support for the referral of the incomplete tyrannosauroid tooth to that family, I coded the specimen for the phylogenetic matrix of Hendrickx and Mateus (2014) comments, which greatly improved the quality of this paper.

Availability of data and material.
All data is available in the Supplementary Information. The author declares no competing interests.

Funding.
The author received no funding for this work.
However, your data and analyses either do not support your main claim or are insufficient to do so. Starting with your dataset, your measurements of NJSM GP 12456 for DB, DC, and DA do not appear congruent with the specimen figured in Fig. 1J, though do seem to match the scale if Fig. 1E. In Fig. 1J, measurements closer to 4 would appear to be more accurate than 2, 2, and 2.5. The scale bars for the photos and your measurements should be double-checked.
Done. I've double checked the scale bars to make sure they are correct. Please see the revised figure.
You also have a substantial amount of missing data for your new specimens in your dataset, and you haven't discussed how this was handled in your PCA. The default in PAST is to fill missing data with column average substitution, which in the   Fig. 2A, and the Tar Heel dromaeosaurid is not plotted in Fig. 4B and 4C, making the argument that either of these teeth have eastern or western affinities insufficiently supported by these analyses. Additions of those specimens and the exclusion of variables with missing data are necessary for these plots to be informative.

dataset will bias all of your specimens towards the tyrannosaur part of your plot (as there are more tyrannosaurs in the dataset than any other group). Given that all three of the new teeth plot in areas of your plots where no other theropod teeth plot (partway between dromaesaurs and tyrannosaurs), it appears that column average substitution of your dataset is having a substantial contribution to the position of your specimens on these plots. As well, eastern taxa are notably excluded. Dryptosaurus is not plotted in
I appreciate this comment, and I have added measurements on the Tar Heel form to the datasets for analysis of the dromaeosaurid tooth. I've gone on the suggestion of reviewer 2 and not performed morphometric work on the tyrannosaur tooth. The affinities of that tooth to tyrannosaurs are still supported by several morphological comparisons and the phylogenetic analysis. I've also removed measurements that are not known for the new teeth to better perform the analysis. Moreover, instead of performing principle components analyses, I've performed a discriminant analysis of the  dataset with characters unknown for the dromaeosaurid tooth removed to better support the referrals. Because the only character in the Larson and Currie dataset unknown for the dromaeosaurid tooth is that of the mesial denticle count, I left the dataset as is for that morphometric analysis. Fig. 1.

In the phylogenetic analysis, you only list shared derived characters between your tyrannosaur specimen and T. rex, but do not list shared derived characters that unite all tyrannosauroids. However, even this analysis does not support your argument that the specimen is a non-tyrannosaurid tyrannosauroid with affinities with Dryptosaurus. Also, one of the four characters you do list, 94) biconvex apical distal denticles, is not mentioned in your description at all nor is it visible in
I have added the shared derived characters that unite all tyrannosauroids to the paper's text and noted the presence of biconvex denticles along the entirety of the carina.
As well, Fig. 1B, 1C, and 1D depict fossils that are not described in the manuscript. If these specimens are figured in this manuscript, they should be described systematically in the text.

This description is of specialist interest given the new records from eastern North America, but any discussion of faunal interchange in premature. In your description, you have demonstrated that you have teeth of a dromaeosaurid and a tyrannosauroid from this formation, but your analyses in their current form are insufficient to demonstrate that these teeth have any biogeographic affinities.
Done. I've modified the paper to focus on the significance of these teeth for contributing to our understanding of Appalachian faunas, and removed the biogeographic speculations.
Reviewer: 2 Comments to the Author(s)

First, I firmly do not think that a phylogenetic analysis should be used on a single tooth, much less a single partial tooth. The phylogenetic analysis of teeth is not a proper use of phylogenetics in my opinion at any rate. To my mind this part of the paper should be eliminated.
This part of the paper was recommended by another researcher who looked at my paper. As it follows in line with many recent studies (e.g., Hendrickx et al., 2014; Young et al., 2014), I have kept it for the sake of making this paper comparable to other, recent works.

Second, the author should use a more recent ordinal analysis of teeth. This is not a deal breaker, but the primary dataset chosen is 13 years old (or 5 yrs old in the case of Larson and Currie) and many others have been produced since then.
Since the Larson and Currie dataset continues to be the one used the most often for morphometric analysis of Cretaceous North American theropod teeth (see Evans  Third, the tyrannosaur tooth should absolutely be removed from the PCA analysis. It is a fragmentary tooth, therefore any measurements taken are not going to be the correct measurement and will provide erroneous results. Or there will be too little data to say much about.
Done. I've removed the tooth.

Fourth, the dromaeosaurid tooth falls outside the dromaeosaurids in the Smith/ Brownstein matrix. And is just part of the miasma of teeth in the Larson and Currie matrix. I would suggest pulling individual taxa from the analyses and talk about comparisons with them instead of consistently saying it is a Saurornithlestesine theropod. Remember that the PCA is using data you input. If there is more information supporting your taxonomic claim that is not included in the quantitative data, then you should discuss this in the text. In PAST you can change the symbol and the color, meaning that you can label individual dinosaur taxa and the higher level taxonomic groups at the same time. This should be done to help you see which species the Tar Heel and Mt Laurel specimens are mostly similar to.
Done. I've instead performed discriminant analyses on the datasets and taking up your suggestion of visualizing the resulting plots using axes 2 and 3. The Mt. Laurel tooth plots firmly within the hull formed by the teeth of Velociraptor in the first DA and firmly with Fifth, this is very important! When using PCA on variables that are measurements, the first axis is almost invariably a reflection of size, not shape. Therefore, you need to show axes 2 and 3. You are welcome to retain axis 1 and 2, but 2 and 3 must be shown in addition. You may also want to consider Centering or z-transforming your data because it can help remove the effect of size, bring outliers closer together, and reflect shape better. Done.

Data
It is a condition of publication that data, code and materials supporting your paper are made publicly available. Does your paper present new data?: Yes

Statement (if applicable):
The data is included in the supplementary material.  Finally, I've removed the biogeographic speculations in line with the comments of the reviewers and editor. I agree that these were presented far too strongly, and I have reorganized the manuscript to act as a faunal characterization. I've also revised the manuscript in accordance with the many minor comments presented in reviewer 2's annotated PDF.

Conflict of interest
I hope the manuscript is now suitable for publication, and thank you for your reviews.  Fig. 1J, though do seem to match the scale if Fig. 1E. In Fig. 1J, measurements closer to 4 would appear to be more accurate than 2, 2, and 2.5. The scale bars for the photos and your measurements should be double-checked.
Done. I've double checked the scale bars to make sure they are correct. Please see the revised figure. Fig. 2A, and the Tar Heel dromaeosaurid is not plotted in Fig. 4B and 4C, making the argument that either of these teeth have eastern or western affinities insufficiently supported by these analyses. Additions of those specimens and the exclusion of variables with missing data are necessary for these plots to be informative.

You also have a substantial amount of missing data for your new specimens in your dataset, and you haven't discussed how this was handled in your PCA. The default in PAST is to fill missing data with column average substitution, which in the Smith et al. (2005) dataset will bias all of your specimens towards the tyrannosaur part of your plot (as there are more tyrannosaurs in the dataset than any other group). Given that all three of the new teeth plot in areas of your plots where no other theropod teeth plot (partway between dromaesaurs and tyrannosaurs), it appears that column average substitution of your dataset is having a substantial contribution to the position of your specimens on these plots. As well, eastern taxa are notably excluded. Dryptosaurus is not plotted in
I appreciate this comment, and I have added measurements on the Tar Heel form to the datasets for analysis of the dromaeosaurid tooth. I've gone on the suggestion of reviewer 2 and not performed morphometric work on the tyrannosaur tooth. The affinities of that tooth to tyrannosaurs are still supported by several morphological comparisons and the phylogenetic analysis. I've also removed measurements that are not known for the new teeth to better perform the analysis. Moreover, instead of performing principle components analyses, I've performed a discriminant analysis of the  dataset with characters unknown for the dromaeosaurid tooth removed to better support the referrals. Because the only character in the Larson and Currie dataset unknown for the dromaeosaurid tooth is that of the mesial denticle count, I left the dataset as is for that morphometric analysis. Fig. 1. 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60 I have added the shared derived characters that unite all tyrannosauroids to the paper's text and noted the presence of biconvex denticles along the entirety of the carina.

In the phylogenetic analysis, you only list shared derived characters between your tyrannosaur specimen and T. rex, but do not list shared derived characters that unite all tyrannosauroids. However, even this analysis does not support your argument that the specimen is a non-tyrannosaurid tyrannosauroid with affinities with Dryptosaurus. Also, one of the four characters you do list, 94) biconvex apical distal denticles, is not mentioned in your description at all nor is it visible in
As well, Fig. 1B, 1C, and 1D depict fossils that are not described in the manuscript. If these specimens are figured in this manuscript, they should be described systematically in the text.
These fossils have been described in previous papers and are there to give the reader a visual map of what fossils are known from the Maastrichtian of NJ.
Alternatively, these figures could easily be excluded from the manuscript. The entire datasets used for analysis, including the  and  should be reproduced in the supplemental data for ease of replication.

This description is of specialist interest given the new records from eastern North America, but any discussion of faunal interchange in premature. In your description, you have demonstrated that you have teeth of a dromaeosaurid and a tyrannosauroid from this formation, but your analyses in their current form are insufficient to demonstrate that these teeth have any biogeographic affinities.
Done. I've modified the paper to focus on the significance of these teeth for contributing to our understanding of Appalachian faunas, and removed the biogeographic speculations.

294
NJSM GP 22949 is the complete crown of a dromaeosaurid dinosaur. Measurements of 295 this specimen are in Table 1. This tooth is heavily recurved, displaying the ziphodont condition. 305 These ridges could represent features of the original morphology of the tooth or be damage from 306 feeding or taphonomic processes. The distal carina preserves a large number of apically hooked 307 denticles that become smaller towards the apex of the crown. These denticles are separated by 308 interdenticular sulci that, along with the serrations, project slightly onto the tooth surface.
In revising my manuscript, I have paid special attention to two major comments given by the reviewers. Firstly, I've removed the PCA of the dataset of  with the tyrannosauroid tooth included on the advice of reviewer 2, provided additional justification for why the tooth is from a tyrannosauroid and probably not a tyrannosaurid, and provided additional information on the results of the phylogenetic analysis.
Secondly, I've redone the PCA and discriminant analyses including the dromaeosaurid tooth such that the analyses of the Larson and Currie dataset include the Tar Heel tooth and the discriminant analysis of the Smith et al. dataset does not include characters that could not be scored for the Mt. Laurel tooth.
Finally, I've removed the biogeographic speculations in line with the comments of the reviewers and editor. I agree that these were presented far too strongly, and I have reorganized the manuscript to act as a faunal characterization. I've also revised the manuscript in accordance with the many minor comments presented in reviewer 2's annotated PDF.
I hope the manuscript is now suitable for publication, and thank you for your reviews.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60 However, your data and analyses either do not support your main claim or are insufficient to do so. Starting with your dataset, your measurements of NJSM GP 12456 for DB, DC, and DA do not appear congruent with the specimen figured in Fig. 1J, though do seem to match the scale if Fig. 1E. In Fig. 1J, measurements closer to 4 would appear to be more accurate than 2, 2, and 2.5. The scale bars for the photos and your measurements should be double-checked.
Done. I've double checked the scale bars to make sure they are correct. Please see the revised figure.
You also have a substantial amount of missing data for your new specimens in your dataset, and you haven't discussed how this was handled in your PCA. The default in PAST is to fill missing data with column average substitution, which in the  dataset will bias all of your specimens towards the tyrannosaur part of your plot (as there are more tyrannosaurs in the dataset than any other group). Given that all three of the new teeth plot in areas of your plots where no other theropod teeth plot (partway between dromaesaurs and tyrannosaurs), it appears that column average substitution of your dataset is having a substantial contribution to the position of your specimens on these plots. As well, eastern taxa are notably excluded. Dryptosaurus is not plotted in Fig. 2A, and the Tar Heel dromaeosaurid is not plotted in Fig. 4B 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59 60 text and noted the presence of biconvex denticles along the entirety of the carina.

294
NJSM GP 22949 is the complete crown of a dromaeosaurid dinosaur. Measurements of 295 this specimen are in Table 1. This tooth is heavily recurved, displaying the ziphodont condition. 305 These ridges could represent features of the original morphology of the tooth or be damage from 306 feeding or taphonomic processes. The distal carina preserves a large number of apically hooked 307 denticles that become smaller towards the apex of the crown. These denticles are separated by 308 interdenticular sulci that, along with the serrations, project slightly onto the tooth surface.
309 Unfortunately, the shape and density of the mesial denticles could not be determined, as the 310 mesial carina is heavily eroded in NJSM GP 22949.
In revising my work, I've paid special attention to the stylistic issues noted by the reviewers. Detailed responses may be found below. I hope the manuscript is now suitable for publication, and thank you for your reviews.