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AnimaliaacceptedgenusAccepted
Gypsonictops

Gypsonictops

Simpson, 1927

GBIF:159397363

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ABOUT

Descriptions(3)

REVISED DIAGNOSIS: These insectivores are medium-sized relative to contemporary mammals, and have submolariform posterior premolars. P 3 of Gypsonictops lewisi has a separate metacone. Both precingulum and postcingulum are present in the more molariform specimens. P 4 is quite molariform, with separated paracone and metacone. Upper molars have narrow stylar shelves, buccally placed paracone and metacone, a stronger postcingulum than precingulum, and a well-developed parastylar area. M 2 is more transverse with better developed lingual cingula than M 1. P 3 has a basined talonid bearing two to three cusps, and a strong posterolingual ridge arising from the protoconid and representing the metaconid. P 4 has a separate protoconid and metaconid and a basined talonid composed of three cusps, with a very poorly developed paraconid. Lower molars are of the standard primitive eutherian pattern, and have elevated trigonids.
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
KNOWN DISTRIBUTION: Campanian, Judith River Formation, Montana; Maestrichtian, Lance Formation, Wyoming; Hell Creek Formation, Montana; Upper Edmonton Formation, Alberta.
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
Gypsonictops SIMPSON, 1927 a, p. 6. TYPE SPECIES: Gypsonictops hypoconus Simpson, 1927 a.
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

AnimaliaChordataMammaliaPilosaGypsonictopidaeGypsonictops

Occurrences with images

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 2026-06-15.

CC0Published 12/31/1972View dataset
GBIF Usage Key
159397363
Dataset Key
fd03f669-c046-46cd-861a-6bf56b7fc989
Origin
source
Backbone Key
4834552
Taxon ID
1A7187CFFFA31714FE59FC41E0FD53F0.taxon
Last Crawled
6/10/2026
Last Interpreted
6/10/2026
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