Abstract by Brandon Theurer

Personal Infomation

Presenter's Name

Brandon Theurer



Degree Level




Abstract Infomation


Geological Sciences

Faculty Advisor

Brooks Britt


Relative abundances and ontogenetic ranges of sphenosuchians and drepanosaurs at the Saints & Sinners Quarry (Late Triassic, Nugget Formation), Utah


The Saints and Sinners Quarry in the Nugget Sandstone of eastern Utah has yielded spectacular remains of nine Late Triassic species. Among these species are sphenosuchians (small, basal crocodylomorphs) and drepanosaurs (small, scratch-digging reptiles with unique arms and an enormous ungual). My research seeks to determine the minimum number of sphenosuchian and drepanosaur individuals and their ontogenetic stages, preserved at the site.  The first method for this is identifying sphenosuchian and drepanosaur left and right humeri and femora and entering this data into a database for analysis. To date, using the humeri and femora counts, we recognize 28-49 sphenosuchian individuals with bodies ranging from about 150 to 775 mm in length. Expanding the count to include other known individuals that did not have femora or humeri preserved expands the count to nearing 100. We also recognize at least six associated to articulated drepanosaur individuals. The spenosuchians carried their limbs directly beneath their body, like mammals and birds, while the drepanosaurs, like extant reptiles, had a sprawling posture.