Resumen

BUCHY, Marie-Céline. Reevaluation of the holotype of Plesiosaurus (Polyptychodon) mexicanus Wieland, 1910 from the ?Upper Jurassic of Mexico: a thalattosuchian, not a sauropterygian. Rev. mex. cienc. geol [online]. 2008, vol.25, n.3, pp.517-522. ISSN 2007-2902.

The holotype of the first sauropterygian described from Mexico, Plesiosaurus mexicanus Wieland, 1910, was recently rediscovered and is here described and discussed for the first time in almost a century. The holotype specimen belongs to an indeterminate metriorhynchine crocodyliform. Doubts remain as to the stratigraphic origin of the specimen, whether Upper Jurassic or Lower Cretaceous. It adds a specimen to the recently recognised wealth of the Mexican Gulf in thalattosuchians.

Palabras llave : Thalattosuchia; Metriorhynchinae; Late Jurassic; Early Cretaceous; Mexico.