A Marine Geosaurine Crocodylomorph from the Kimmeridgian Sabinal Formation of Oaxaca, Southern Mexico

We report the first record of a geosaurine crocodylomorph from Kimmeridgian marine deposits of the Sabinal Formation at the Llano Yosobe locality in Oaxaca, southern Mexico. Although fragmentary, the fossil is probably part of either a dentary or maxilla preserving dental pits and three labiolingually compressed upright teeth. The presence of sinuous apicobasal ridges that reach the pseudoserrate cutting edges on the crown is consistent with Geosaurinae. However, the specimen is unique in possessing crown ridges that are evenly distributed over both labial and lingual surfaces. Excavations at the Llano Yosobe locality and its surroundings are ongoing, thus further discoveries of geosaurine remains are anticipated in the near future.