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Hello all, I’ve had this tyrannosaur tooth for a little while now, but haven’t been able to narrow down a species. I’m curious if it is possible to ID it any further. Would love to learn more. It was found in the Judith River Formation (Hill County, MT), and is ~13.5mm. Thank you all for your help in advance!

Perhaps one of the most exciting scientific papers in a while about the genetic diversity of the Tyrannosaurid genus Tyrannosarus itself (the genus that includes the famous and well documented T-rex) was just announced and published (or at least the abstract of it)!!! Image Credit: Dalman et al. 2023 (abstract) and the Society for Vertebrate Paleontology (SVP). https://vertpaleo.org/wp-content/uploads/2023/10/2023_SVP_Program-Final-10032023.pdf At the Society for Vertebrate Paleontology's annual meeting for 2023, Paleontologists Dr. Sebastian Dalman, Dr. Philip J. Currie, and seven other experienced Paleontologists and experts on the Tyrannosaurid theropod dinosaurs published an abstract on October 21, 2023 about a new species of Tyrannosaurus (Tyrannosaurus mcraensis) from the Hall Lake Formation dating 72 Million Years ago to the Campanian-Maastrichtian Cretaceous of what is now New Mexico!!! This not only gives insights on the origins of the genus Tyrannosaurus, but validates previous hypothesis over the years (at least since 2013) that a unique giant Tyrannosaur from southern Larmidia (now Western North America) that lived during the Campanian-Maastrichtian Cretaceous!!! Names given to this animal over the years include Alamotyrannus brinkmani and Tyrannosaurus brinkmani. A Digital Reconstruction of the Tyrannosaurus species Tyrannosaurus mcraensis and it's size compared to an average Human, April 2022. Image Credit: Artist LancianIdolatry https://twitter.com/LancianIdolatry/status/1511016414252978182 This is especially true given for how long the debate has been raging on the Validity ofThe species Tyrannosaurus mcraensis was when fully grown the same size of the averaged size adults of the later Tyrannosaurus rex from the later Maastrichtian Cretaceous. By the look of things with the Paper and the experienced paleontologists and Tyrannosaur experts who authored it, it seems just by looking at its abstract it will be be far more through and accurate than the recent Gregory S. Paul Paper from 2022 and maybe even prove the validity of the debate Tyrannosaur species Tyrannosaurus vannus from the 70-66 Million Years ago dated Javelina Formation of what is now Texas. But I'm wondering if anyone has more information on this study and the potential of it's results?

Purchased this tooth that was listed a theropod tooth. I think/hope it may be Dromaeosaurus. It has been repaired. From Hill County, MT, Judith River Formation. Seems to have a mesial carina twist & chisel shaped distal denticles. CH: 13mm CBW: 4mm CBL: 7mm Mesial: 5/mm Distal: 3/mm

A new paper that describes Furcatoceratops elucidans a new centrosaurine ceratopsid from the Judith River Formation of Montana Unfortunately it's paywalled https://www.sciencedirect.com/science/article/abs/pii/S019566712300188X Anthony Maltese posted this This was the Ava skeleton Blog by A. Maltese http://rmdrc.blogspot.com/2015/02/avaceratops-layout.html Reposted by D. Evans

I purchased this tiny tooth from The Judith River Formation, North of Havre, MT found on a private ranch close to the border. I am unable to identify the tooth, it appears Thescelosauridae however I don't think Thescelosaurs have been found in Judith River. Measures 0.18" Any idea what this could be?

These teeth were sold as a baby tyrannosaurid and a dromaeosaurid/bird respectively. Some other specimens from this lot have been posted here if I recall. But they are from North of Havre, Montana close to the Canadian border. Apparently they are from quite an old collection from around 1950-70s. The provenance should place it solidly in Judith River Formation. Since these teeth were selling somewhat quickly, I just grabbed them and decided on figuring it out later. The first tyrannosaurid tooth does have some similarities to Dromaeosaurus with the mesial twist, but I could be wrong. The second tooth is a bit more confusing. I'm guessing it is Zapsalis-type with those striations which would make it Saurornitholestes. I don't think it's bird compared to bird teeth from other deposits. It's probably not one of those Campanian microraptorians either, and it's probably too big even at this size to be bird or micro. 1st tooth: Length=6.3mm; Distal Density=17.5/3mm; CBL=2.9mm; CBW=1.8mm 2nd tooth: Length=5.8mm; Distal Density= ±11-12/mm (?); CBL=2.6mm; CBW=1.3mm Serration density for the 2nd tooth might not be too accurate since it was extremely difficult to even get to that number. Not sure how to go about getting CH, but it's probably a little bit more than the length since the tips are worn. 1st tooth might be good as is since with that small root section, that probably makes up for what would be a longer crown. 1st Tooth 2nd tooth

Hello, I'm asking about the following bone end. It's said to be from the "Judith River Formation North of Havre, MT". Seller thinks it might be a bird bone since it's hollow but doesn't look like theropod, what do you think? @Troodon confirmed it's not dinosaur and might be turtle, is there enough to tell? And how would one make that distinction?

Hi all, A bulk purchase of channel deposit material from the Judith River Formation of Montana has yielded these teeth, each of which appears to have some ankylosaurian affinities. I have read @Troodon’s guide on this very topic, but alas I still would like a second look at some of these teeth. I do not have the capacity to take very good macro photos, but I hope that these are passable at least for an initial glance. The scale of each tooth. The numbering on the bottom is centimeters while the numbering on top is in inches Tooth 1: I’m 99% sure this one is ankylosauridae Tooth 2: Might actually be Ceratopsid, but the presence of “denticles” is what’s making me post this one. Tooth 3: Ditto for this tooth, may be Ceratopsid, but we’ll see. Tooth 4: 80% sure this one is Nodosauridae with feeding wear. The opposing side has the distinctive “shelf” that gives the tooth a mitt look. Let me know if a picture of the other side is needed. Tooth 5: Also thinking nodosaur on this one, fairly confident Thanks everyone!

Edited 6/20/23: added Furcatoceratops elucidans More and more dinosaur material is becoming available from the Judith River Formation. I see lots of misidentified material and some with questionable localities that might fit other deposits. I would like to summarize what I believe is currently known and published. If you see any omissions or errors, please let me know. Not a lot of good maps out there to show the formation but here are two. In general, the exposures are in North Central Montana. Horner describes the formation on the western end is near the east end of the Sweetgrass Hills (very thick about 152 meters) and thins to less than 3 meters to its eastern edge Saco, MT. Bound by marine deposits Claggett Formation beneath and Bearpaw Fm above. More important, for collectors buying material is to be aware of the counties that have the majority of exposures they include but not exclusive to: Hill County, Blaine County, Phillips County, Western Part of Valley County, Fergus County, Wheatland County, Northern Valley County, Western Part of Garfied County, Big Horn County .You can see by the maps why a good provenance is vital to an ID. Stratigraphic range: Late Cretaceous, Middle to Upper Campanian 79.7 - 75.2 Ma Red _ Judith River Fm in Montana Faunal List: Updated 10/22/2022 (excludes Avialae) Lots of changes in recent years so older hard copy books are most likely out of date e.g. Dinosauria 2nd edition. This list was developed based on looking at a number of different reference sources, not Wikipedia, and like most lists some paleontologists or collectors may have different opinions, which is fine. The Judith deposit is very similar to those of the Belly River Group however you would not guess it by the variety of different dinosaurs that are described in this list particularly with the herbivores. Denver Fowler has even questioned if there is any justification to calling it Judith anymore since its continuous with Canadian Units. Will leave that for a different discussion since it probably will never happen. Edited 11/25/22 Tyrannosauridae: - Tyrannosaur indet. (Tom Holtz 2021) - Daspletosaurus wilsoni (Warshaw & Fowler 2022) - Aublysodon mirandus - nomen dubium Dromaeosauridae: - Dromaeosaurus albertensis (Matthew & Brown 1922) - Saurornitholestes sp. - Dromaeosaurid? - Zapsalis abradens (Although included on most faunal list this tooth morphology was shown to be a premaxillary tooth of a Saurornitholestes (DPF) (Currie & Evans 2019) it is therefore not valid Theropods: - Troodon formosus (Leidy 1856) - cf Richardoestesia gilmorei - cf Paronychodon lacustris - Ornithomimid indet. (spp.) - Ornithomimid large bodied (PO & Longrich 2007 DPFm) - Cenagnathid indet (Personal Observation) - Theropod indet Pachycephalosauridae: - Pachycephalosaurid indet. - Colepiocephale lambei (Sternberg 1945) Ankylosauria: - Nodosaurid indet (cf Edmontonia) - Zuul crurivastator (Arbour & Evans 2017) - Ankylosaurine ? Ceratopsidae: - Avaceratops lammersi (Dodson 1986) - Judiceratops tigris (Leidy 1856) - Medusaceratops lokii (Ryan et al. 2010) - Mercuriceratops gemini (Ryan et al. 2014) - Spiclypeus shipporum (Mallon et al. 2016) - Furcatoceratops elucidans (Hiroki Ishikawa et al. 2023) - Ceratopsid indet. - Leptoceratopsid indet? Hadrosauroidae: - Probrachylophosaurus bergei (Fowler & Horner 2015) - Brachylophosaurus canadensis (Sternberg 1953) - Hadrosaurinae indet. - Lambeosaurinae indet. - Corythosaurus sp. (Takasaki et al. 2022) Other Ornithischians: - Orodrominae indet? PO- Personal Observation in my collection Reference - Takasaki, Ryuji; Chiba, Kentaro; Fiorillo, Anthony R.; Brink, Kirstin S.; Evans, David C.; Fanti, Federico; Saneyoshi, Mototaka; Maltese, Anthony; Ishigaki, Shinobu (2022-10-23). "Description of the first definitive Corythosaurus (Dinosauria, Hadrosauridae) specimens from the Judith River Formation in Montana, USA and their paleobiogeographical significance". The Anatomical Record. doi:10.1002/ar.25097. ISSN 1932-8486 -Tom Holtz Theropod guild structure and the tyrannosaurid niche assimilation hypothesis: implications for predatory dinosaur macroecology and ontogeny in later Late Cretaceous Asiamerica (2021) Canadian Journal of Earth Science -Mallon JC, Ott CJ, Larson PL, Iuliano EM, Evans DC (2016) Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA. PLoS ONE 11(5): e0154218. doi:10.1371/journal.pone.0154218 -Sahni A. The vertebrate fauna of the Judith River Formation, Montana. Bull Am Mus Nat Hist. 1972; 147: 321–412. -Schott RK, Evans DC, Williamson TE, Carr TD, Goodwin MB. The anatomy and systematics of Colepiocephale lambei (Dinosauria: Pachycephalosauridae). J Vert Paleontol. 2009; 29: 771–786 -Longrich NR. Judiceratops tigris, a new horned dinosaur from the middle Campanian Judith River Formation of Montana. Bull Peabody Mus Nat Hist -Ryan MJ, Russell AP, Hartman SC. A new chasmosaurine ceratopsid from the Judith River Formation, Montana. In: Ryan MJ, Chinnery-Allgeier BJ, Eberth DA, editors. New perspectives on horned dinosaurs: the Royal Tyrrell Museum Ceratopsian Symposium. Bloomington: Indiana University Press; 2010. pp. 181–188 -Freedman Fowler EA, Horner JR (2015) A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana. PLoS ONE 10(11): e0141304. doi:10.1371/journal.pone.0141304 -Rogers RR. Sequence analysis of the Upper Cretaceous Two Medicine and Judith River formations, Montana: nonmarine response to the Claggett and Bearpaw marine cycles. J Sediment Res. 1998; 68: 615–631. -Fowler DW (2017) Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America. PLoS ONE 12(11): e0188426. https://doi.org/10.1371/journal. pone.0188426 -Dinosaurs under the Big Sky, Jack Horner, 2001 Mountain Press Publishing Co.

I figured as long as I'm asking about a 2" finger bone, I might as well throw in a 2" caudal vert This is from the Judith River formation, Hill County, Montana. Thank you!!

Hello! I recently bought this ankylosaur tooth (in fact it arrived today) and I was wondering if it could be from a nodosaur. Thank you! (Judith river formation hill county Montana)

I have a few vertebrae I was hoping to get identified. These are 3 that I don't have any others that are alike. I tried to search online and the oval shaped one looks like possibly a Pachy but wasn't sure. These were all found on the Judith River Formation Montana, Hill County. first 4 is the one that I thought was Pachy, 2nd 4 I am not sure, 3rd 4 might be Hadrosaur?

Hi everyone ! Got this tooth for a while . Currently labelled as indeterminate hadrosaur tooth size 0.68" from Hill county , Judith river formation . I wonder if we can ID to the species name ? note : This tooth have a denticles(?) on the edge of the tooth . Thank you in advance Guns

These are a couple smaller vertebrae and a bone I found on the Judith River Formation, I was hoping to get an opinion on what dinosaur they would be from. Thanks.

As I understand it there are three described Tyrannosaurs from the Two Medicine and Judith River Formations -- Albertosaurus, Gorgosaurus and Daspletosaurus. I have read that research done on teeth from these three Tyrannosaurs has concluded that isolated teeth are statistically impossible to assign to a specific genus because they are so similar. Now, I know that there are a number of form members that have quite extensive collections and have spent time and money studying these teeth, and it is my believe (having spent 35 years in the minerals exploration business) that private researchers probably know as much if not more than the academics. It has been my experience that academics rarely spend their own nickel buying their own equipment, conducting field work, and collecting specimens to conduct their research. I also know from first-hand experience that statistical evaluation alone can lead one down the wrong path and to the conclusion 'it needs more study.' While I am not a 'true' collector, my interests are hands-on fossil and mineral specimens that tell a story to interest kids in general science. My question is are there any general observations about Two Medicine and Judith River Formation theropod teeth that one might use to assign a probable genus to these teeth? It seems that assigning a genus to isolated teeth from the large adult theropods is quite possible, juvenile teeth seem more problematic -- but juvenile teeth are what I can afford. I would appreciate observations you might be willing to share.

Hi all! Newbie here. Just starting out collecting. I saw this tooth for sale but seller does not appear to know exactly what it is. What I can say is its from Judith River and 3/4 inches longs. It looks to me like a dromeosaur tooth from the guides I found on here but figured it never hurts to ask! Thanks for any help. cretaceous-judith-river-theropod-tooth-5a.jpg.webp cretaceous-judith-river-theropod-tooth-5.jpg.webp cretaceous-judith-river-theropod-tooth-5d.jpg.webp cretaceous-judith-river-theropod-tooth-5c.jpg.webp cretaceous-judith-river-theropod-tooth-5b.jpg.webp

This is my first attempt at getting a Dromeosaurus albertensis tooth from Judith River fm. I've largely been avoiding buying dromeosaurids like the plague that aren't Acheroraptor or Saurornitholestes. Provenance: Hill County, Montana The tooth is repaired, and I had to realigned it while restabilizing it with butvar. The tooth doesn't seem to perfectly fit together, or too much butvar ended up in-between. There does not appear to be any serrations on the mesial edge, and it doesn't appear to have any trace of serrations, at least not that I can see with a macroscope. I don't think it's Saurornitholestes sp. due to the serrations not having the distinct hooked shape. I'm not 100% sure whether or not it's Tyrannosauridae indet., but I don't think it is, but the robust dromeosaurids are supposedly very similar at first glances. Any help or clues is appreciated. If any pictures are insufficient, I can try and take better photographs.

I saw a tooth of an Tyrannosaurid Indet. The price looks good and the size is 3.3 inches including the repaired lower end. The seller told that this is from Judith River Formation, Northern Montana, and No restoration. Can anyone find any evidence of restoration? I can't find any... And.. this is another one from the same seller. This is also Tyrannosaurid indet, and from JRF.