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Paronychodon lacustris

Paronychodon lacustris

Cope, 1876

GBIF:159397314

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Descriptions(3)

Figures 8 S, T; 9 J, K
Sahni, Ashok (1972): The vertebrate Fauna of the Judith River formation, Montana. Bulletin of the American Museum of Natural History 147 (6): 319-416, DOI: 10.5281/zenodo.3382461, Hdl: http://hdl.handle.net/2246/1099
The genus was originally described by Cope (1876 a, p. 256) from detached teeth obtained from the Judith River Formation. Zapsalis abradens was also described by Cope (1876 b, p. 345) from the same area and is a larger, worn tooth of Paronychodon. Teeth referable to Paronychodon lacustris were named Tripriodon caperatus (Marsh, 1889 b, pl. 3, figs. 18 - 22) because of a supposed identity as the incisors of the multituberculate Meniscoessus Cope (= Dipriodon Marsh). Clemens (1963 b, pp. 85 - 86) showed that Meniscoessus incisors were significantly different from Paronychodon and Estes (1964) has demonstrated that P. lacustris is a carnivorous dinosaur. The rare genus Paronychodon is represented in the collection by about six teeth of various sizes. The largest (AMNH 8522, fig. 8 S, T) has a length of 13 mm. and a basal width of about one-third the length, and the smallest (AMNH 8523, fig. 9 J, K) has a height of 4.8 mm. and a basal width of about 2.8 mm. Other differences in morphology also exist. AMNH 8522, from Clambank Hollow, is relatively less curved than teeth of Deinodon. At least four ridges were present on the internal side of the crown but these have been worn down. The smaller teeth are more curved and are not denticulated on the posterior or anterior side, although sharp ridges are present.
Sahni, Ashok (1972): The vertebrate Fauna of the Judith River formation, Montana. Bulletin of the American Museum of Natural History 147 (6): 319-416, DOI: 10.5281/zenodo.3382461, Hdl: http://hdl.handle.net/2246/1099
Paronychodon lacustris COPE, 1876 a, p. 256. Zapsalis abradens COPE, 1876 b, p. 345. Tripriodon caperatus MARSH, 1889 b, pl. 3, figs. 18 - 22.
Sahni, Ashok (1972): The vertebrate Fauna of the Judith River formation, Montana. Bulletin of the American Museum of Natural History 147 (6): 319-416, DOI: 10.5281/zenodo.3382461, Hdl: http://hdl.handle.net/2246/1099

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CLASSIFICATION

Taxonomic Classification Tree

AnimaliaChordataReptiliaDinosauriaDeinodontidaeParonychodonParonychodon lacustris

MULTIMEDIA

Media Files(2)

FIG. 8. A. Chamops segnis. AMNH 8486, labial view of left dentary. B. Lingual view. Both x 5. C. AMNH 8488, lingual view of left maxilla. D. Labial view. Both x 5. E. cf. Xenosauridae, AMNH 8498, labial view of left maxilla. F. Lingual view. Both x 5. G. Peltosaurus piger, AMNH 8495, lingual view of left maxilla, x 5. H. AMNH 8494, lingual view of right dentary, x 5. I. Paraderma bogerti, AMNH 8504, lingual view of right maxilla. x 5. J. Parasaniwa wyomingensis, AMNH 8499, lingual view of left dentary, x 5. K. Leptochamops denticulatus, AMNH 8491, lingual view of right maxilla, x 5. L. Exostinus lancensis, AMNH 8497, lingual view of right maxilla, x 5. M. Deinodon horridus, AMNH 8513, posterior view of isolated tooth. N. Lateral view. Both x 13. 0. AMNH 8515, lateral view of anterior dentary tooth. P. Posterior view. Both x 13. Q. AMNH 8514, posterior view of?premaxillary tooth. R. Lateral view. Both x 12. S. Paronychodon lacustris, AMNH 8522, lingual view of isolated tooth. T. Labial view. Both x 12. U. Kritosaurus cf. K. breviceps, AMNH 8525, lateral view of isolated tooth. V. Posterior view. Both x 1 2. W. Procheneosaurus altidens, AMNH 8527, labial view of isolated tooth. X. Anterior or posterior view. Both x 12. Y, Z.?Sebecosuchia, AMNH 8549, views of an solated tooth. Both x 10.

Imageimage/png© Sahni, AshokSahni, Ashok

FIG. 9. A, B. Edmontonia lorngiceps, AMNH 8543, lateral views of an isolated tooth, x 1. C, D. Palaeoscincus costatus, AMNH 8542, lateral views of an isolated tooth, x 12. E, F. Thescelosaurus cf. T. neglectus, AMNH 8536, lateral views of an isolated tooth, x 10. G, H. Ceratopsidae, AMNH 8540, lateral views of an unworn tooth, x 12. I. Dromaeosaurus albertensis, AMNH 8516, lateral view of an isolated tooth, x 12. J, K. Paronychodon lacustris, AMNH 98523, lateral views of an isolated tooth, x 12. L, M. Troodon formosus, AMNH 8518, lateral ~~~~~~~~~~~~~~~~~~~~~~~~~~~~3. views of an isolated tooth, x 12. N. 0,?Stegoceras validus, AMNH 8530, lateral views of an isolated tooth, x 1-. Dinosaur egg shell fragments. P. AMNH 8545, external view of shell (Class B). Q. Internal view. Both x 10. R. AMNH 8546, external view of shell (Class B). S. Internal view. Both x 10. T. AMNH 8548, external view of shell (Class C). U. Internal view. Both x 10. V. AMNH 8547, external view of shell (Class B). W. In- ternal view. Both x 10. X. AMNH 8544, external view of shell (Class A), x 10.

Imageimage/png© Sahni, AshokSahni, Ashok

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Source Information

The vertebrate Fauna of the Judith River formation, Montana

checklist

This dataset contains the digitized treatments in Plazi based on the original journal article Sahni, Ashok (1972): The vertebrate Fauna of the Judith River formation, Montana. Bulletin of the American Museum of Natural History 147 (6): 319-416, DOI: 10.5281/zenodo.3382461, Hdl: http://hdl.handle.net/2246/1099

GEOLOGIC INVESTIGATION of the Late Cretaceous Judith River Formation in the area just north of the Judith River on the Missouri River in north-central Montana has resulted in the discovery of varied vertebrate forms. The beds are mainly freshwater continental deposits consisting of crossbedded channel sandstones, gray siltstones, and carbonaceous shales with occasional seams of lignitic coal. The stratigraphic sequence consists of the Marias River Shale overlain by the Eagle, Claggett, Judith River, and Bearpaw formations. The last four constitute the Montana Group. The Judith River Formation is Campanian in age as determined by its position between the fossiliferous marine Claggett and Bearpaw shales.

The fauna was obtained from the upper 50 feet of the formation. The bone concentration in the productive sandstone is the result of size sorting leading to underrepresentation of the larger dinosaurs. Three orders of mammals are represented, the Eutheria by a single genus, the Allotheria by five, and the Metatheria by at least three genera. Teiid and parasaniwid lizards are frequent. Only a fraction of the large number of described dinosaur genera, however, is represented in the collection by isolated teeth. Fish and amphibians form a sizable portion of the fauna.

Vertebrates from the Judith River Formation are more primitive than, but generally similar to, later Maestrichtian species. The mammals differ from their descendants in the Lance Formation at the species level. The community structure and the paleoecology of the fauna of the Judith River Formation resemble those of the Lance Formation. The greatest difference between the two communities is the greater variety of dinosaurs in the earlier formation.

Sahni A, plazi (1972). The vertebrate Fauna of the Judith River formation, Montana. Plazi.org taxonomic treatments database. Checklist dataset https://doi.org/10.5281/zenodo.3382461 accessed via GBIF.org on 2026-06-19.

CC0Published 12/31/1972View dataset
GBIF Usage Key
159397314
Dataset Key
fd03f669-c046-46cd-861a-6bf56b7fc989
Origin
source
Backbone Key
8692180
Taxon ID
1A7187CFFFC11776FE54FE00E048524A.taxon
Last Crawled
6/10/2026
Last Interpreted
6/10/2026
View on GBIFSource Reference