- Copyright © 2013, The Paleontological Society
A Maastrichtian rudist fauna composed of the radiolitids Biradiolites aguilerae Böse, B. Cárdenasensis Böse, Huasteca ojanchalensis (Myers), Tampsia floriformis Myers, and Trechmannites rudissimus (Trechmann), the hippuritids Caribbea muellerriedi (Vermunt) and Praebarrettia sparcilirata (Whitfield) sensu lato, and the plagioptychids Coralliochama gbohemi Böse and Mitrocaprina tschoppi (Palmer) is described from the Cárdenas Formation in San Luis Potosí State, Mexico. Abundant fossil material and excellent preservation of a number of specimens allowed observation of both the internal and external shell characters and their ontogenetic and eco-phenotypic variability. The description of some hitherto insufficiently known species has been enhanced and/or completed, making easier their subsequent identification and allowing their unequivocal generic assignation. Two new genera, Huasteca and Trechmannites, are proposed for two already known species of radiolitids. The Cárdenas Formation exhibits a continuously exposed sequence in the vicinity of Cárdenas. Thus, precise stratigraphic location of all fossil localities and their rudist associations, ranging from the early to the early late Maastrichtian, has been possible.