7 The Campanian Crucible: A synthesis of vertebrate paleobiogeography and ecosystem dynamics in Laramidia (Posters)

Laramidia’s Campanian deposits reveal vertebrate diversification, geographic isolation, and provincialism, and its fossil record informs paleoecology and biogeography. This session synthesizes research on evolution, endemism, WIS dynamics, and underexplored geochronology across this Late Cretaceous landscape.

Monday, 18 May 2026
8:00 AM - 5:30 PM
Alvarado D/E

First Occurrence of the Durophagous Mosasaur Globidens from New Mexico

Paper number: 7-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Tsaya Canyon, located in the San Juan Basin of New Mexico, preserves the Middle Campanian intertonguing of the predominantly terrestrial, freshwater, and brackish Menefee Formation within the overlying marine Cliff House Sandstone. Reported here is the first occurrence of the durophagous mosasaur Globidens, represented by two isolated teeth, within the Tsaya Canyon marine assemblage. Dental characteristics include a globular crown devoid of carinae and a lightly anastomosing enamel structure that thickens towards a blunt apex. On one specimen, the crown slants posteriorly, with the enamel marking its maximum thickness apicoposteriorly. Both teeth feature a crater-shaped wear facet on the apex, indicative of a durophagous diet. One tooth also displays four shallow, apicomarginally situated spalling surfaces that are apicobasally elliptical in outline and do not extend completely through the enamel. This wear pattern may be indicative of attrition resulting from repeated tooth-to-tooth contact. An apical nubbin is absent from both teeth, though this may be due to wear.

 

The co-occurence of Globidens with additional durophagous taxa including the actinopterygians Paralbula and cf. Albula, as well as the batoids Protoplatyrhina and Pseudohypolophus, suggest hard-shelled prey was foundational for the paleoecology of Tsaya Canyon. Inoceramid bivales, a known prey item for Globidens, are present in the marine sandstones of Tsaya Canyon, however there is a strong stratigraphic separation between these shells and the vertebrate fossils collected at this site. Although the Tsaya Canyon specimens are contemporaneous with Globidens alabamaensis and Globidens dakotensis, they cannot be reliably assigned to either species due to tooth preservation and wear on both specimens. Thus, an assignment of these specimens to Globidens sp. is herein designated. These teeth mark the first specimens of Globidens documented from New Mexico, providing additional data regarding the geographic distribution of the genus in the Western Interior Seaway. 

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410692

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