A reassessment of the taxonomic status of Paraglyptodon chapadmalalensis (Ameghino in Rovereto) (Mammalia, Cingulata, Glyptodontia)

CRUZ, LAURA E.; FERNICOLA, JUAN C.; TAGLIORETTI, MATÍAS L.; TOLEDO, NÉSTOR

La Rioja

Jornada; XXVII Jornadas Argentinas de Paleontología de Vertebrados; 2013

The holotype of Paraglyptodon chapadmalalensis (MACN-Pv 6162, fragment of the dorsal carapace) was discovered by Florentino Ameghino from Mar del Plata and Chapadmalal area (Buenos Aires, Argentina) in sediments assigned to Chapadmalalan Stage/Age. Castellanos created to Paraglyptodon like as the antecessor of Glyptodon and included in Paraglyptodon all know species of Glyptodontinae recovered from ?horizontes pre-Ensenadenses?, and in Glyptodon all species from ?Horizontes pampeanos?, so the latter was restricted to the Quaternary. However, juvenile specimens of Glyptodon and recent works on some of these in which morphological differences are described in the osteoderms from the dorsal carapace reveal another hypothesis. The superficial surface of the osteoderms in MACN-PV 6162 present central figure (CF) surroundings by six to seven, exceptionally eight peripheral figures (PF) of the smaller size. The CF is slightly elevated in relation of the PF and almost all osteoderms present a central concavity. The central sulci are wide, deep, and delimited. The radial sulci are wide and slighter delimited. The sutures between osteoderms are slack and preserved separating the PF of adjacent osteoderms. This ornamentation is recognizable in the middle-dorsal section of the dorsal carapaces of the juvenile stage of Glyptodon sp. (e.g., MCA 2013). Also, the size of the osteoderms of these specimens are similar to that the holotype of Paraglyptodon Chapadmalalensis. So, we could not identify distinguishing features indicating their separation as distinct genus, and all of the morphological features describes previously as diagnostic of Paraglyptodon chapadmalalensis were also observed in juvenile stages of Glyptodon sp.