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Reassessment of Yurgovuchia Pelvic Material and Theropod Diversity in the Early Cretaceous Lower Yellow Cat Member of the Cedar Mountain Formation of Central Utah

Semester: Summer 2023

Presentation description

UMNH VP 26015 represents a previously unrecognized theropod taxon in Doelling's Bowl. The lack of a supraacetabular ridge on the ilium differentiates it from ornithomimids and tyrannosauroids. The anteroventral process of the ilium, the supraacetabular hood and the shape of the cuppedicus and brevis fossae are most similar to Falcarius. The pubis is similar to allosaruids, ornithomimids, tyrannosaurids, Falcarius, and Achillobator in the propubic orientation of the pubis but differs from allosaruids, ornithomimids, tyrannosaurids, Falcarius, Deinonychus, Achillobator, Adasaurus, and Velociraptor in lacking a prepubic component to its pubic boot. The blade-like ischial shaft with a distal anterior obturator process of UMNH VP 26015 is similar to Falcarius, Deinonychus, and most known dromaeosaurids and differs from allosauroids, compsognathids, tyrannosauroids, and Achillobator which have rod-shaped ischial shafts. The socket on the ischium for articulation with the ilium is most similar to the condition in Falcarius. The Doelling's Bowl Bone Bed has also yielded pelvic material from two dromaeosaurs, the holotype of Yurgovuchia (UMNH VP 20211.18) and an unnamed dromaeosaurid (UMNH VP 21752). The holotype of the pelvis of Yurgovuchia was described as a proximal left pubis, but upon further inspection it is a distal right pubis. UMNH VP 26015 was found close to the holotype of Yurgovuchia, however, the cross-sectional shapes of the pubic shafts are different. The three pubes found in this area indicate a diverse theropod ecology in the Yellow Cat Member during the Lower Cretaceous. Further inspection of this material is needed to determine which taxa UMNH VP 26015 represents.

Presenter Name: Rachel Jorgensen
Presentation Type: Poster
Presentation Format: Virtual
Presentation #36
College: Mines & Earth Sciences
School / Department: Geology and Geophysics
Research Mentor: Mark Loewen
Date | Time: Thursday, Aug 3rd | 10:30 AM