SUPERFAMILY GONDWANATHERIOIDEA - A PREVIOUSLY UNRECOGNIZED RADIATION OF MULTITUBERCULATE MAMMALS IN SOUTH-AMERICA

Multituberculates were the longest-lived order of the Class Mammalia a nd, during the Mesozoic and early Cenozoic, were among the most divers e and abundant representatives of the class. However, until the recent discovery of two Cretaceous teeth, one from South America and one fro m Africa, they were known only from northern continents. Additional ma terial of the South American form Ferugliotherium has confirmed its mu ltituberculate affinities and indicates that it may be a derived membe r of the Suborder Plagiaulacoidea. New specimens provide evidence that two other South American forms, Gondwanatherium and Sudamerica, are a lso multituberculates and that they are closely related to Ferugliothe rium. Gondwanatherium and Sudamerica, each possessing highly specializ ed hypsodont molars, were previously thought to be the earliest known representatives of the Edentata, to be involved in the origin of edent ates, or to represent a previously unknown higher taxon of mammals. Ho wever, there are detailed similarities in gross dental morphology, ena mel microstructure, and inferred direction of jaw movement-among Ferug liotherium, Gondwanatherium, and Sudamerica. All three genera are here regarded as representatives of a highly derived, endemic radiation of South American multituberculates and are allocated to the superfamily Gondwanatherioidea. Multituberculates were therefore more common elem ents of Late Cretaceous and early Paleocene mammalian faunas of South America than previously recognized.