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Pachycephalosaurid/Thescelosaurus Tooth Identification
Troodon posted a topic in General Fossil Discussion
One of the more frequent questions I get asked is to identify teeth from Thescelosaur's and Pachycephalosaurid's since they are so similar in appearance. So when I run across a paper that has anything associated with it, I'll take a look. Recently I read a 2014 paper by Clint Boyd of the School of Mines in SD, that described skull of Thescelosaurus neglectus** from the Hell Creek Formation, with some nice photos of the dentition's. It motivated me to do some additional research to get a better understanding of these teeth using scientific papers instead of anecdotes, supplier listings or my perceptions which I found out were incorrect. My resources being limited I did not find much out there in the public domain and read that little is know especially with Pachycephalosaurid's dentition's. So I'll present what I found and hope there are members of this forum that have access to additional information that can enlighten us. The dentitions of these two families of dinosaurs are heterodontid so the jaws contain different tooth morphologies although some species of Pachy's may not be. To my surprise, the book Dinosauria (2nd ed) states that dentary teeth (from the mandible) from Pachycephalosaurid's are only known from a few species and only Stegoceras from the HC and LC formations. Not sure if that statement is still valid, the book was published in 2007. Thescelosaurus neglectus** Premaxillary Teeth (pm1-6) There are 6 teeth in each Premax. The photo gives you a great image of what they look like, all are bulbous in shape with some curvature in the crown. Also added an isolated tooth, two views from my collection. Maxillary Teeth (mt1-20) There are 20 teeth in each maxillary and take a spade shape. They are compressed, the crown is ornamented with fine ridges from the tip to the base. The more posterior the tooth the larger the wear facet and the tooth takes a different look, looses it's pointed tip. The first photo one can see all of the premaxillary teeth in "A" the anterior teeth in "B" and posterior teeth in "C". I also added a couple of additional pictures isolated teeth one anterior and one posterior Dentary Teeth (dt1-20) The teeth on this skull are poorly exposed see photo below (dt1-7) on one side and only the first three (dt) are visible on the other but they appear to take the shape of smaller but not as robust premaxillary teeth. Since the dentary teeth in this skull so not provide us a good view I used another source Sternberg 1937 paper. In this image only # 8 is a dentary tooth, 1 & 2 are premaxillary, 4-7 are maxillary. The main difference between this and a maxillary tooth is a much more pronounced center ridge near the center of the crown. These teeth are larger than maxillary teeth with a crown that is higher and more pointed. I also added a couple of isolated teeth from my collection. Paper : The cranial anatomy of the neornithischian dinosaur Thescelosaurus neglectus** by Clint A. Boyd ** NOTE There are two species of Thescelosaurus in the Hell Creek & Lance Formation. T. neglectus and T. garbanii. Distinguishig teeth between them I don't believe is possible.- 55 replies
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Hi all, Unfortunately I have no location info on this tooth which i know is really important but the seller can't obtain this information as it was from an old collection of someone that passed away. Does the morphology match Ankylosaurus or nodosaur rather than Pachy and Thescelosaurus? Thanks Jai
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From the album: Dinosaur Fossils collection
Thescelosaur rooted tooth Locality: Hell Creek, Montana, USA Geological Age: Cretaceous (65-70 MYA) Specimen Size: 1/2" Long & 3/8" Wide