Cranial anatomy of a Maastrichtian (Upper Cretaceous) mosasaur (Squamata, Mosasauridae) from north-east Mexico

  • Marie Céline Buchy Universität Karlsruhe, Geologisches Institut, Postfach 6980, D-76128 Karlsruhe, Germany. Current address: Museo del Desierto, Apartado Postal 307, 25000 Saltillo, Coahuila, Mexico.
  • Eberhard Frey Geowissenschaftliche Abteilung, Staatliches Museum für Naturkunde, Erbprinzenstrasse 13, D-76133 Karlsruhe, Germany.
  • Wolfgang Stinnesbeck Universität Karlsruhe, Geologisches Institut, Postfach 6980, D-76128 Karlsruhe, Germany.
  • José Guadalupe López-Oliva Universidad Autónoma de Nuevo León, Facultad de Ciencias de la Tierra, Apartado Postal 104, 67700 Linares, N.L., Mexico.
Keywords: Mosasauridae, Early Maastrichtian, Méndez Formation, north-east Mexico.


We here describe the first mosasaur from Mexico known by significant cranial remains, from the late Early Maastrichtian Méndez Formation of Nuevo León, north-east Mexico. The specimen comprises a fragmentary skull and parts of the mandibles. Some anatomical features suggest a juvenile animal. The skull possesses a rostral tuberosity on the premaxilla, as well as a combination of features known from different mosasaur genera, like its frontopremaxillary suture situated caudal to the external naris, its prefrontal and postorbitofrontal being in contact lateral to the orbit, associated with the supra- and infrastapedial processes of its quadrate which almost contact one another. Despite being clearly distinct from any hitherto described mosasaur, the affinities of this specimen with other mosasaurs remain obscure, not only because of incompleteness, but also because of the poorly understood biological significance of the characters used for the classification of Mosasauridae.

Regular Papers