Paper No. 221-8
Presentation Time: 10:45 AM
MOSASAUROIDS FROM THE STATE OF PUEBLA, CENTRAL MEXICO
In Mexico, the record of Mosasauroidea is scarce and is restricted to the northeastern part of the country. Recent paleontological work carried on in the State of Puebla, Central Mexico, has resulted in the discovery of remains of marine reptiles from two localities: San José de Gracia and Huehuetla. San José de Gracia Quarry is of Turonian age; the mosasaur material includes the anterior part of the premaxilla and the right maxilla of the same individual. Tooth roots largely exposed in medial view and the strongly recurved teeth are diagnostic characters of the members of the Subfamily Yaguarasaurinae, which is a small and poorly known group of Turonian mosasaurs. The geographic distribution of this subfamily includes Italy, Colombia and Texas. The Mexican record represents a midpoint in the Proto-Atlantic between United States, Colombia and Europe. The locality of Huehuetla is of Aptian-Cenomanian age. Three specimens were recovered: one consists of a series of articulated caudal vertebrae; the second includes a set of thoracic vertebrae with a fragmented hindlimb; and the third includes the skull, the anterior axial skeleton and part of the forelimbs. These specimens posses some diagnostic characters of Aigialosauridae, such as the intramandibular joint, the quadrate rami of parietal extending posteriorly to the foramen magnum and the tail laterally compressed with elongate, posteriorly angled neural and haemal spines on caudal vertebrae; they resemble the taxa described from the Turonian Mexican locality of Vallecillo, Nuevo Leon. Aigialosaurs are primarily registered from Europe and there are some fragmentary records from United States. The Huehuetla specimens represent the most complete basal mosasauroids specimens, and the southernmost record in the American continent; possibly they are the oldest. Aigialosauridae is considered, by some authors, as the basal group of the Superfamily Mosasauroidea; the Mexican specimens are important because they will provide new information for the interpretation of the evolutionary relationships of the group.