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Troodon posted a topic in General Fossil DiscussionA number of collectors are very interested in Triassic Dinosaur tooth material, however, lots of misinformation exists, partially because little is known and dealers want to sell product. My knowledge is very limited so I tried to put together an assemblage of current information that has been published so that we can all become better versed on this topic. I'm not saying its complete but its the best I can do with my limited knowledge. Most technical papers on this subject are outdated, difficult to read for a novice and not complete enough. Fortunately a recent, legible paper was published in 2015 by Heckert & Lucas that has helped me. I've tried to extract the pertinent information, associated with teeth, since that what most collectors are interested in. First let me get on my sandbox and say that we should NOT assume that what is being sold is accurately described regardless who is selling it or how much you like a dealer. Very little is known and even less is described. If a seller insists what he has identified is accurate, have him show you the technical documents that supports his diagnosis. There are a number of theropods and archosaurs in these assemblages that have serrated teeth so identification is difficult. Triassic dealers similar to those in the Kem Kem which label everthing Spinosaurus like to label everything Coelophysis. Just be cautious..its your money. Almost all the teeth you see sold come from New Mexico so I will focus in that region. A Map of New Mexico with the Triassic outcrops shown below as well as the associated Counties. The numbers correlate to the stratigraphic formations shown below in Figure 4. Figure 4 The Zuni Mountains in West-Central NM are from the lower Chinle Group (Bluewater Creek Fm) and contain Tetrapod fossils amphibians and phytosaurs and aetosaurs. Dinosaurs are possible but nothing is diagnostic. Faunal List of the lower Chinle Group Zuni Mountains Northern/West Central New Mexico has yielded some of the most interesting Vertebrate Fossils most associated with Coelophysis at Ghost Ranch. Included in this group are the Petrified Forest and Rock Point Formation of the western counties. Chindesaurus bryansmalli, Tawa hallae and Daemonosaurus chauliodus are considered valid a dinosaurs in the Petrified Forest Fm. Coelophysis bauri is valid from the Rock Point Formation. Faunal List of the Petrified Forest and Rock Point Formation - Key on this list is Coelophysis bauri in the Rock Point Fm Northeasten New Mexico (Bull Canyon and Redonda Formations). Heckerts 2015 paper comments that dinosaur fossils remains are rare in the Bull Canyon Formation. The coelophysoid Gojirasaurus quayi has been described but its taxonomic placement is uncertain. Herrerasauridae tooth fragments have been found but nothing has been assigned to a taxon. Heckerts & Lucas 2015 Paper on Triassic Vertebrate Paleontology in New Mexico https://libres.uncg.edu/ir/asu/f/Heckert_Andrew_triassic.pdf Bull Canyon Formation 2001 Paper on Vertebrate Fauna https://nmgs.nmt.edu/publications/guidebooks/downloads/52/52_p0123_p0151.pdf Latest placement ( Hans-Dieter Sues et al 2011 ) Identifying Coelophysis bauri Teeth - There is lots of variation their teeth and I will show a few types. The Museum of Northern Arizona publication Coelophysis describes the teeth as follows: All the teeth are recurved Premaxillary teeth: rounded cross-section, smaller teeth are ribbed but smooth on larger ones. None show serrations. Maxillary Teeth: the first tooth is recurved with no serrations, second tooth has serrations only on the posterior carina. All the other maxillary teeth have serrations on both edges. Some of the teeth the serrations may be limited to the upper part of the anterior (mesial) edge. Dentary Teeth: the first seven teeth lack serrations, eight tooth serrations only on the posterior edge. Subsequent teeth have serrations on both edges. The first four teeth are elliptical (rounded) in cross-section being compressed after that. Anterior teeth may contain ridges. Serrations are very fine 8 to 9 per millimeter on the posterior (distal) edge. (other publications say 7/mm) Distal Carina Denticles Premaxillary, Maxillary and Dentary teeth shown - Dentary tooth Maxillary Tooth Anterior Denticles Posterior Maxillary Tooth Paper on Coelophsis Teeth by Currie and Buckley Coelophisis.pdf Additional images of the teeth with no supporting info Good overall paper on C. bauri but does nothing to increase our knowledge on how to describe its teeth https://www.researchgate.net/publication/292525024_The_paleobiology_of_Coelophysis_bauri_Cope_from_the_Upper_Triassic_Apachean_Whitaker_quarry_New_Mexico_with_detailed_analysis_of_a_single_quarry_block Other Theropods Gojirasaurus quayi : one tooth was described with the holotype however it was found isolated and cannot be positively assigned to this species. (Added a few pages below) Chindesaurus bryansmalli : not aware of any skeletal material Daemonosaurus chauliodus The paper does not get into detail on the teeth. See below http://rspb.royalsocietypublishing.org/content/royprsb/278/1723/3459.full.pdf Tawa hallae : http://www.thefossilforum.com/applications/core/interface/file/attachment.php?id=503864
Recently acquired a Triassic Theropod Dinosaur Tooth from New Mexico, USA Coelophysis bauri tooth Location: Bull Canyon Formation, Norian, Upper Triassic, San Miguel County, New Mexico, USA 210 Million Years Old Obtained from Palaeontologist Byron Blessed Below are some sample photos, I am looking around for a small device in order to try magnify the serrations on the tooth as there are so many and it is very hard to count the number per mm. I have read the books and journals on Coelophysis bauri that were linked on this forum previously and they are so interesting! Will try to post some close-ups of the serrations, the other side of the tooth and the bottom of the tooth soon. Wiki Link: https://en.wikipedia.org/wiki/Coelophysis_bauri Journal is called 'Acritical re-evaluation of the Late Triassic dinosaur taxa of North America'
The evolution of theropod hands has taken quite a journey from the late Triassic to the late Cretaceous. This paper tries to explore the evolution of early theropods Coelophysis bauri and Megapnosaurus rhodesiensis Abstract: The origin of the avian hand, with its reduced and fused carpals and digits, from the five-fingered hands and complex wrists of early dinosaurs represents one of the major transformations of manus morphology among tetrapods. Much attention has been directed to the later part of this transition, from four- to three-fingered taxa. However, earlier anatomical changes may have influenced these later modifications, possibly paving the way for a later frameshift in digit identities. We investigate the five- to four-fingered transition among early dinosaurs, along with changes in carpus morphology. New three-dimensional reconstructions from computed tomography data of the manus of the Triassic and Early Jurassic theropod dinosaurs Coelophysis bauri and Megapnosaurus rhodesiensis are described http://onlinelibrary.wiley.com/doi/10.1111/joa.12719/full/ The evolution of the manus of early theropod dinosaurs is characterized by high inter- and intraspecific variation Authors Daniel E. Barta, Sterling J. Nesbitt, Mark A. Norell First published: 8 November 2017 DOI: 10.1111/joa.12719 joa12719.pdf