New Mexico Geological Society Annual Spring Meeting — Abstracts

Fossil dinosaur remains from the Upper Cretaceous McRae Formation in Sierra County, New Mexico, have been collected and studied for over a century, albeit sporadically. Dinosaur taxa that have been previously reported include Tyrannosaurus rex (although probably representing a different species of that genus),  Alamosaurus sp., an ankylosaurid, and large fenestrate chasmosaurines tentatively referred to as Torosaurus, but which likely represent a new taxon.This assemblage has led to an age assignment of Late Maastrichthian (Lancian), however that age assignment needs more robust biostratigraphic data to be verified.Given that dinosaur fossils are used to assign an age to the McRae Formation and that the assemblage may contain taxa which are of uncertain taxonomic placement, all new materials have potential biostratigraphic and/or taxonomic value. Recently, field parties from the New Mexico Museum of Natural History and Science have made an attempt to revisit previously reported dinosaur localities not currently submerged by Elephant Butte Reservoir as well as prospect for new localities. Newly discovered dinosaur material includes a partial hadrosuarid post-cranial skeleton, an unusually large ceratopsid epijugal from a previously known locality as well as numerous large indeterminate specimens awaiting excavation.  These new discoveries are from the middle to upper part of the Hall Lake Member and will provide data to determine the upper age limit of the McRae Formation.