New Mexico Geological Society Annual Spring Meeting — Abstracts

The small, brackish water and marine ray Pseudohypolophtls mcnultyi Thurmond is a common component of Late Cretaceous North American shallow marine selachian assemblages. Teeth of this ray have an external morphology that is nearly identical to those of other ray species such as Hypolophus and Myledaphus, but the histology of the P. mcnultyi teeth is very distinctive. Thus, the teeth of P. mcnultyi have an osteodentine root with either a layered or homogenous orthodentine crown. However, many times, the necessary histological work to identify these teeth is not undertaken. In this study, teeth from three localities NMMNH L-297, NMMNH L-342 and NMMNH L-4730 were studied to identify these ray teeth to species. These localities are in the Rio Puerco valley of central NM, NMMNH L-342 and L-4730 are in the upper Coniacian Dalton Sandstone, and NMMNH L-297 is in the Santonian Hosta Tongue of the Point Lookout Sandstone. All three localities represent shallow marine depositional settings. The teeth from these three localities show a homogenous orthodentine crown and an osteodentine root. Seasonal growth lines can be seen in the enamel. The Pseudohypolophus teeth from these three sites are nearly identical in their internal structure and can be assigned with certainty to P. mcnultyi. Thus, they represent the first verified records of P. mcnultyi from the Cretaceous of New Mexico.