A tale of two clades: Comparative study of Glyptodon Owen and Glyptotherium Osborn (Xenarthra, Cingulata, Glyptodontidae)

ZURITA A.E.; GILLETTE D.; CUADRELLI, F.; CARLINI, ALFREDO A

GEOBIOS

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2018 p. 1 - 33

0016-6995

Glyptodon and Glyptotherium represent the most conspicuous taxa of late Neogene andPleistocene glyptodonts in South America and North America, respectively. The earliestrecords of Glyptodon in South America are 1.07 Ma (late early Pleistocene, Calabrian),although the possibility that ?Paraglyptodon uquiensis? represents a Pliocene specimen ofGlyptodon cannot be rejected. Glyptotherium originated from South American ancestry innorthern South America or Central America about 3.9 Ma (early late Pliocene, Zanclean) orearlier. The diversity of South American Glyptodon is currently under study, but preliminaryevidence would indicate that no more than three species (G. munizi, G. elongatus, and G.reticulatus) are valid, plus a possible new Andean species. In turn, according to the updatedtaxonomy proposed herein, Glyptotherium includes two chronospecies. The earliest species,Gl. texanum, differs only slightly from the latest species, Gl. cylindricum. The relationship ofGlyptodon and Glyptotherium has been problematical since the discovery of the NorthAmerican lineage, at first identified as various species of Glyptodon, and later considered aseparate genus. Glyptodon is recognized as a natural group, and recent taxonomic andphylogenetic revisions place all North American glyptodontines into Glyptotherium. In thispaper we propose a detailed morphological comparison between the southern South Americanspecies of Glyptodon and Glyptotherium in order to identify diagnostic differences andpotential synapomorphies. Both genera can be distinguished mainly by differences in theskull, mandible, dentition, dorsal carapace, and caudal armor, Glyptodon being somewhatlarger than Glyptotherium. Both clades show a highly conservative evolution, which could beinterpreted as an anagenesis. The scarce records of glyptodonts in Central America showmore morphological affinity with Glyptotherium than with Glyptodon.