Troodon Posted September 9, 2022 Share Posted September 9, 2022 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List: Updated 10/22/2022 (excludes Avialae) Lots of changes in recent years so older hard copy books are most likely out of date e.g. Dinosauria 2nd edition.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) - 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. 7 1 Link to post Share on other sites
Troodon Posted September 9, 2022 Author Share Posted September 9, 2022 Identification of teeth: Tyrannosauridae - Daspletosaurus wilsoni recently described and a Gorgosaurus sp is most likely present. Aublysodon mirandus (an unserrated Premaxillary tooth) is nomen dubium (not valid) A paper that came out in 2005 which was authored by Phil Currie et al. studied isolated teeth from this Campanian period looking at tooth and serration morphology. Their conclusion was that "it is difficult to quantifiably distinguish these teeth reliably by taxon". Important to try to figure out its position if there is any hope to identify it to a specific species when described. Ref: Samman, T., Powell, G.L., Currie, P.J., and Hills, L.V. 2005. Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification. Acta Palaeontologica Polonica 50 (4): 757–776 Juvenile Premaxillary Teeth There is a quantitative process described in a new paper that may help differentiate between Daspletosaurini and Gorgosaurus teeth. Its described in the attached topic. Identification Tyrannosaurid Teeth From North America - General Fossil Discussion - The Fossil Forum Dromaeosaurus albertensis Dentition includes 4 Premaxillary, 9 Maxillary, 11 Dentary teeth AMNH FR 5356 ---Witmer Lab's Replica Maxillary Teeth: (Holotype) - CH : 11-18 mm (Avg: 12.4mm) - CBR: 0.5-0.61 (Avg: 0.55) - CHR: 1.62-2.26 (Avg: 1.77) Dentary Teeth: (Holotype) - CH : 8.5-14.8 mm (Avg: 11.3mm) - CBR: 0.56-0.74 (Avg: 0.62) - CHR: 1.5-2.22 (Avg: 1.84) Serration Density (Holotype) Distal (5mm): 15-20 (Avg:17.7) (3.54/mm) Mesial (5mm): 13.8-18.8 (Avg:16.4) (3.29/mm) DSDI: 0.82-1.08 (Avg: 0.93) Smith et al. (2005) Distal range 3.0-5.0/mm, Mesial range 1.8-3.5/mm Key Features: -Teeth are small, holotype <18mm and NOT compressed. -Mesial carina is close to the midline near the tip, and not far from the tip twists toward the lingual side (Lingual Twist) -Both Mesial and Distal carinae of any premaxillary tooth are on the lingual side of the tooth -Dentary teeth cannot be distinguished from maxillary teeth in type specimen -Serrations found on the mesial carina at least as far back as the 8th dentary tooth. -Serration Density 0.93 so Distal is greater than Mesial Edge Serrations : Chisel Shaped Examples of Positions: Premaxillary Tooth #2: Labial View on Left, Lingual View on Right Cross Section Premaxillary Base Premaxillary tooth #1 Maxillary Tooth: Lingual view Dentary Tooth - Anterior, Lingual view on Right, Anterior view on Left, Enlargement of Distal Denticles on Far Left, Cross Section of Base on far Right Saurornitholestes sp. (Will use characteristics/data from S. langstoni) Dentition includes 4 Premaxillary, 12 Maxillary, 15 Dentary teeth Premaxillary Teeth: (sample size 7) -CH : 8.3-12.6 mm (Avg:10.3 mm) -CHR : 1.68-2.31 (Avg: 2.03) Lateral Teeth: (sample size 137) - CH : 2.8-13.5 mm (Avg: 9.17mm) - CBR: 0.25-0.59 (Avg 0.46) - CHR: 1.20-2.60 (Avg: 1.98) Serration Density Lateral Teeth (sample size 16) - Distal (5mm): 15-30 (Avg: 22.3) (4.46/mm) - Mesial (5mm): 25.0-35.5 (Avg: 29.9) (5.98/mm) - DSDI: 1.16-1.60 (Avg: 1.29) Serration Density Premax teeth - Mesial (5mm): 30 - Distal (5mm): 15.5 Key Features: -Premaxillary Teeth : -3 long flutes/ridges on labial side -Both Carina are denticulated -Mesial side is denticulated to cervix - Lateral Teeth: -Distal Denticles hooked distally toward the tip of the tooth -Can have blood grooves -Teeth are small and recurved Distal Serrations : Hooked at very tip of denticle Premaxillary Tooth Anterior Dentary Tooth Lateral Tooth Reference: -Philip J. Currie,David C. Evans Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta 2019 -Taxonomic identification of isolated theropod teeth: The case of the shed tooth crown associated with Aerosteon (Theropoda: Megaraptora) and the dentition of Abelisauridae Christophe Hendrickx, Emanuel Tschopp , Martín Ezcurra 2929 -Theropod teeth from the Judith River Formation of Southern Alberta, Canada. In Dinosaurs Systematics, 1990 6 2 1 Link to post Share on other sites
Meganeura Posted September 9, 2022 Share Posted September 9, 2022 Great and important write up, thank you @Troodon! Link to post Share on other sites
Troodon Posted September 10, 2022 Author Share Posted September 10, 2022 cf Richardoestesia isosceles Typically found in most late cretaceous deposits however its perplexing because it appears to be ABSENT from Judith River deposits. I show it here for information if something should pop up and to let collectors know to be weary of ones being sold from the JRF. Some paleontologists view it as nomen dubium simply because it's a tooth taxon that has not been sufficiently diagnosed. Others believe it's an anterior tooth of R. gilmorei. Or does it belong to a different group of animals, my choice. Identification is pretty easy: shape of an isosceles triangle, can be slightly recurved, very compressed, serrated carinae. cf Richardoestesia gilmorei The genus of Richardoestesia is poorly understood and its taxonomic placement is uncertain, known from a small jaw (Currie et al. 1990). Isolated teeth are quite varied in shape and size and no premaxillary teeth have been identified with certainty. Its denticles are minute some of the smallest found in JRF. Sankey et al (2002) describes these teeth as small, recurved 3 to 12 mm in height. Denticles are small to minute with 5 to 11/mm depending on size. Mesial denticles are usually not present and are minute when present. another example Currie identifies a longform version of this tooth but other that what you see in this illustration very little to add Looks like the density is 5/mm on both edges Paronychodon lacustris Another mystery tooth and also a tooth taxon and a non-serrate form. Several morph types are shown in the attached photo. Crowns can be conical, elliptical, slightly recurved and a few have a flat lingual side. Most teeth have longitudinal ridges. Reference: -Small theropod and Bird Teeth from the Late Cretaceous (Late Campanian) Judith River Group, Alberta. Julia Sankey, Donald Brinkman, Merrilee Guenther, Philip Currie 2002 -Theropod teeth from the Judith River Formation of Southern Alberta, Canada. In Dinosaurs Systematics, 1990 -Vertebrate Microfossil Assemblages ed Sankey and Baszio 2008 Indiana Press -CFS 196 Investigations on Canadian Dinosaurs, Sven Baszio 1997 1 1 1 Link to post Share on other sites
Troodon Posted September 11, 2022 Author Share Posted September 11, 2022 Zuul crurivastator Zuul is an Ankylosaurini with teeth slightly different than what we see in Maastrichtian deposits. Unfortunately, the holotype did not preserve its teeth very well, but we do have a good understanding of what the anterior dentary ones look like. Anterior Dentary teeth: The image below are anterior dentary teeth. They are leaf-shaped, labiolingually compressed and have long straight roots. These are 6.1 mm wide along the base and 7 mm tall with an aspect ratio slightly less than 1. The Crowns in this portion of the jaw bear 12-14 diamond-shaped cusps, with the apex crown slightly offset. A cingulum (bulbous ridge) is present along the base of the crown. Lingual View Example of one I saw sold online Maxillary teeth: We have less information on the morphology of the Maxillary teeth Labial View - highly worn 5mm across Lingual View Penkalski (2018) believes these teeth most strongly resemble those of Scolosaurus sp. from the Dinosaur Park Formation. Example shown below. Reference: Arbour, Victoria M.; Evans, David C. (2017). "A new ankylosaurine dinosaur from the Judith River Formation of Montana, USA, based on an exceptional skeleton with soft tissue preservation". Royal Society Open Science. 4 (5): 161086. Bibcode:2017RSOS....461086A. doi:10.1098/rsos.161086. PMC 5451805. PMID 28573004 Revised systematics of the armoured dinosaur Euoplocephalus and its allies., N. Jb. Geol. Paläont. Abh. 287/3 (2018), 261–306 Article Stuttgart, March 2018 , Paul Penkalski Other Ankylosaurine? One cannot assume there is only one Ankylosaurine in these deposits. Multiple ones exist in the equivalent deposits of the Belly River Group. If the tooth does not match the morphology of Zuul then it should be assigned to Ankylosaurinae indet. Nodosaurid indet. (cf Edmontonia) Teeth are typically a bit larger than those of ankylosaurinae and pretty distinctive. Leaf shaped with a bulbous cingulum ridge present at the base of the crown. No strong prominent center ridge with pocket on lingual side. Lingual and Labial sides shown Reference: Teeth and Taxonomy in ankylosaur, W. Coombs Jr. In Dinosaur Systematics 1990 3 1 Link to post Share on other sites
Troodon Posted September 11, 2022 Author Share Posted September 11, 2022 Colepiocephale lambei C. lambei is a small Pachycephalosaurid and I have not found much on its dentition. I'm not sure you can assign any isolated teeth to this pachycephalosaur since other species may be present but not described. The skull of this dinosaur is very small so the teeth equally small. Stegoceras validum is similar and we have a good picture of its dentition. Specifics on its teeth are shown in the table Other Pachycephalosaurs are most likely present, the teeth are distinctive in this fauna. Their crowns are asymmetrical with a straight root. The largest tooth in this photo is 10 mm References: Dental assessment of Stegoceras validum (Ornithischia: Pachycephalosauridae) and Thescelosaurus neglectus (Ornithischia: Thescelosauridae): paleoecological inferences Michael Naylor Hudgins, Philip J. Currie, Corwin Sullivan Ryan K. Schott , David C. Evans , Thomas E. Williamson , Thomas D. Carr & Mark B. Goodwin (2009) The anatomy and systematics of Colepiocephale lambei (Dinosauria: Pachycephalosauridae), Journal of Vertebrate Paleontology, 29:3, 771-786, DOI: 10.1671/039.029.0329 2 Link to post Share on other sites
Troodon Posted September 11, 2022 Author Share Posted September 11, 2022 Ceratopsid indet. Teeth from large bodied Ceratopsian are indistinguishable from one another. Sellers that identify or suggest a specific genus is unfortunately more of a deceptive sales practice than fact or just ignorance on there part. Unless a tooth is found with an identifiable skull it's a "Ceratopsian indet." Complete Tooth Partial Crowns Spitters Leptoceratopsid? There is a good chance these are present, unfortunately I have not seen anything published. Single rooted teeth with a distinctive crown. 2 1 1 Link to post Share on other sites
Troodon Posted September 12, 2022 Author Share Posted September 12, 2022 Hadrosaurid indet. Hadrosaur teeth from this deposit are difficult to identify to a genus. Not only do you have the similarity in the crowns but there are certainly more species that have yet to be described. There are characteristics that MAY help point to a Subfamily but that difficult for most and we really do not have a good understanding of the number of species that exist in this deposit. Sellers that identify or suggest a specific genus is unfortunately more of a deceptive sales practice than fact or just ignorance on their part. Unless a tooth is found with an identifiable skull it's a "Hadrosaurid indet." Maxillary teeth an have a center ridge that does not reach the apical end and a pinch or narrowing of the sides Complete Dentary Teeth Some Dentary crowns have small denticles or papillae Partial Crowns Top Left is a Maxillary Tooth Partials and Spitters ALTHOUGH THE TEETH OF THE NEXT TWO ARE KNOWN AND DESCRIBED IT DOES NOT GUARANTEE THERE ARE NOT OTHER SPECIES IN THIS DEPOSIT WITH SIMILAR CHARACTERISTICS...... YOU CAN DESCRIBE THEM AS SIMILAR TO (cf) Probrachylophosaurus bergei Teeth from maxilla possesses a single median carina, many of which are subtly sinusoidal, as in Brachylophosaurus. The edges of the crowns have papillae that are slightly smaller but more prominent than those of Brachylophosaurus . The dentary teeth have a prominent median carina with no secondary carinae. The median carinae are straight or rarely extremely subtly sinusoidal. The edges of the crowns have faint papillae that are much less prominent than the papillae on the maxillary teeth. MOR2919 Brachylophosaurus canadensis Maxillary teeth are similar to those in Probrachylophosaurus. A single median carina bisects the crown longitudinally without reaching its apical end. Small papillae are present along the edges of the crown. The dentary teeth have a prominent median carina with no secondary carinae. The median carinae are straight or rarely extremely subtly sinusoidal. Not sure if papillae are present MOR 1072 Reference: -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. -Albert Prieto-Marquez (2005) New information on the cranium of Brachylophosaurus canadensis (Dinosauria, Hadrosauridae), with a revision of its phylogenetic position, Journal of Vertebrate Paleontology, 25:1, 144-156 Corythosaurus sp. Maxillary teeth possess a straight or slightly curved center ridge at the midline of each tooth. The apical half of the tooth small papillae are present. Dentary teeth are not described. 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 2 1 2 Link to post Share on other sites
Troodon Posted September 12, 2022 Author Share Posted September 12, 2022 To wrap this up this topic up let's address Troodon teeth. Please note that the Troodontid, Pectinodon in that topic is not found in the JRF 2 Link to post Share on other sites
Troodon Posted October 25, 2022 Author Share Posted October 25, 2022 Updated topic to reference information obtained on : - 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 1 1 Link to post Share on other sites
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