FIRST MATERIAL OF THE GIANT ALLIGATOROID DEINOSUCHUS FROM THE ALLISON MEMBER OF THE MENEFEE FORMATION, SAN JUAN BASIN, NEW MEXICO

Beginning in 2011, yearly expeditions to exposures of the Allison Member of the Menefee Formation in the San Juan Basin of northwestern New Mexico have been conducted by the Zuni Dinosaur Institute for Geosciences, the Western Science Center, and the Southwest Paleontological Society. This project, undertaken by academics, citizen scientists, and volunteers alike, has enriched our understanding of southern Laramidia during the Upper Cretaceous (middle Campanian).

Here we report the first material of the enormous alligatoroid Deinosuchus sp. recovered from the Menefee Formation, including two caudal vertebrae and several large, inflated osteoderms with deep and widely spaced surface pitting, which are distinctive for the genus. Our material is among the oldest known for Deinosuchus; the upper part of the Allison Member is approximately 79 to 80 million years old, which roughly correlates to material recovered from the lower shale member of the Aguja Formation in Texas and from the Blufftown Formation in Georgia. This also extends the record of Deinosuchus known from the San Juan Basin, with fossils previously uncovered in the younger Fruitland Formation at approximately 76 million years old.