CONICET | Buscador de Institutos y Recursos Humanos

Glyptodonts constituted one of the most bizarre groups of mammals ever to have evolved in America. During the end of the Pleistocene, these herbivorous animals reached gigantic sizes, with forms that varied between one and two tons of body mass. Their most remarkable anatomical features are the presence of an essentially immobile dorsal carapace, hypselodont trilobate teeth, elephantine hind-limbs, and a masticatory apparatus telescoped well below the cranium. Traditionally, the classification and phylogeny of the glyptodonts were based on characters of the external surface of osteoderms and the morphology of the caudal tube, in contrast with other mammals, where cranial and postcranial features have played a central role. Recent investigations of this clade based on cranial and postcranial characters resulted in new phylogenetic hypotheses that support the monophyly of the glyptodonts and suggest new internal phylogenetic relationships, and that do not support traditional systematic arrangements. These include the existence of a basal dichotomy, with the subfamily Propalaeohoplophorinae (late Oligocene-early Miocene), historically considered paraphyletic, positioned as the sister group of the remaining glyptodonts (late Miocene-early Holocene). The paraphyly of Hoplophorinae, and of two of the seven hoplophorine tribes, Hoplophorini and Plohophorini, are also noteworthy., This analysis also strongly supports other novel phylogenetic arrangements, such as a clade comprised of the genera Panochthus and Neosclerocalyptus. Finally, the combination of phylogenetic and stratigraphic information allows recognition of an important gap in the paleontological record of at least 10 Ma.