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Need Id On Hell Creek Dino Teeth


-Andy-

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Hi all, I acquired a small set of raptor teeth from Hell Creek, but two of these teeth does not seem like they belong to dromaeosaurids to me.

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They seem to be curved like a plesiosaur tooth, and have no serrations at all. The cross-section is oval, with a small black core in the middle.

Any help on id-ing these would be appreciated.

Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday!

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Hey Andy

Your tooth on the left looks to be Richardoestesia and my guess for the lack of serrations would be that they wore off from natural feeding wear or sometime in between falling out of its mouth and the 65MY it took to be found.

The one on the right however falls into the category of Nomen dubium "just not diagnostic enough". It could belong to a pterosaur, amphibian, dinosaur, fish or a number of other critters.

A friend has told me that there is a lot of research being done on the theropods of Hell Creek and that some species might merge together with one being lost.

There are also quite a few varied theories including one that there were no dromeosaurids in the HC formation and that the teeth that have been referred to them are actually juvenile Rex and Nano etc.

Cheers

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Thank you.

I didn't realize Richardoestesia could have long curved teeth, I assumed their teeth was similar to typical dromaeosaurids like the one below.

Richardoestesia.png

Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday!

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Andy

There are two species of Richardoestesia currently in the Hell Creek: R.‭ ‬gilmorei‭‬ & ‬R.‭ ‬isosceles. The first one has more of a curvature on it and the other typically looks like an isosceles triangle.

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Hey Andy

Your tooth on the left looks to be Richardoestesia and my guess for the lack of serrations would be that they wore off from natural feeding wear or sometime in between falling out of its mouth and the 65MY it took to be found.

The tooth without serrations is actually more similar to Paronychodon than to Richardoestesia because AMNH 3018 (type of Paronychodon lacustris) lacks serrations. In the past, all the flattened theropod teeth with serrations were included in Paronychodon, but as rightly noted by Larson and Currie (2013), the presence of serrations is too discrete to be ontogenetic and instead is of taxonomic significance and the serrated "Paronychodon" teeth are identical to Zapsalis abradens.

Larson, D. W.; Currie, P. J. (2013). "Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time". In Evans, Alistair Robert. PLoS ONE 8: e54329. doi:10.1371/journal.pone.0054329.edit

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I have this one, which has been identified as Richardoestesia gilmorei; it is not serrated. Length is 13/32".

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"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

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>Paleontology is an evolving science.

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Thank you for the replies guys.

I will label it as Richardoestesia gilmore for now, but shall continue to look at similar Hell Creek dino teeth to see if I can gain further insight.

Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday!

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  • 2 weeks later...

For stratigraphic reasons the identification of Richardoestesia-like teeth from the Hell Creek as R. gilmorei and R. isosceles is tenuous because: (1) R. gilmorei and R. isosceles are known from 75 million year old rocks, whereas the Hell Creek teeth are 10 million years younger; and (2) the holotypes of R. gilmorei and R. isosceles could be the same species with a heterodont dentition because R. isosceles teeth share with R. gilmorei teeth mesial denticles smaller than the distal denticles (Williamson and Brusatte 2014; see also Longrich 2008). So no matter the taxonomy of Richardoestesia-like forms, it would be difficult not to rule out a Richardoestesia-like form from Hell Creek possessing heterodonty b/c the non-dinosaurian archosauromorph Azendohsaurus has a mix of sauropodomorph- and ornithischian-like teeth (which was why the hypodigm of Azendohsaurus laarousii at one time was considered to be composite of sauropodomorph and ornithischian remains).

Longrich N (2008) Small theropod teeth from the Lance Formation of Wyoming, USA. In: Sankey JT, Baszio S, editors. Vertebrate Microfossil Assemblages: Their Role in Paleoecology and Paleobiogeography. Bloomington: Indiana University Press. pp. 135–158.

Williamson TE, Brusatte SL (2014) Small Theropod Teeth from the Late Cretaceous of the San Juan Basin, Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution. PLoS ONE 9(4): e93190. doi:10.1371/journal.pone.0093190

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