THE LAST SURVIVOR OF A NEOGENE LINEAGE OF GLYPTODONTIDAE (XENARTHRA, MAMMALIA): PLOHOPHORUS AMEGHINO IN THE LATEST PLIOCENE-EARLIEST PLEISTOCENE OF THE PAMPEAN REGION (ARGENTINA)

SOFÍA I. QUIÑONES; CUADRELLI, FRANCISCO; DE LOS REYES MARTIN; ALFREDO E. ZURITA

Otro; Reunión de Comunicaciones de la Asociación Paleontológica Argentina (RCAPA); 2022

Xenarthra are divided in two groups, Pilosa (anteaters and sloth) and Cingulata (armoredxenarthrans). In this latter, Glyptodontidae constitutes one of the most enigmatic animals that everlived in South America until its extinction in the latest Pleistocene-Early Holocene. Recentphylogenetic proposals show an early Miocene divergence into two clades, one of northern origin(Glyptodontinae) and the other with austral origin, which groups the majority of the recognizeddiversity. Despite the fact that the knowledge of the austral clade was recently improved, severaltaxa need urgent taxonomic and phylogenetic studies in order to understand their evolutionaryhistory. One particular case is represented by the “Plohophorini”, a tribe that traditionally includedseveral genera (Plohophorus, Pseudoplophophorus, Phlyctaenopyga, Stromaphorus andStromaphoropsis), from the late Miocene-Pliocene of Pampean and Northwestern regions ofArgentina and Uruguay. In this contribution we present a new and terminal species of Plohophorus(Xen-44, CCA-19 y CCA-20 “Colección Cementos Avellaneda”. Olavarría, Buenos Aires)exhumed from the El Polvorín Formation, of the Pampean region of Argentina, which in turnrepresents the first case of a Neogene genus of glyptodonts surviving into the Plio-Pleistocene limit(ca. 2.53 Ma). Plohophorus sp. nov. differ from P. figuratus by the well developed lacrimaltubercle; short, stright and wide descending process; occipital condyles with greater transversedevelopment; a third series of peripheral figures between the second and the third series of proximalosteoderms of the caudal tube. The preliminary phylogenetic analysis shows that Plohophorus sp.nov.+ P. figuratus cluster together, being the sister taxa of Ps. absolutus + Ps. benvenutti,corroborating that the well characterized species of Plohophorini of Uruguay and the Pampeanregion of Argentina constitute a natural group. In turn, the comparative anatomical study shows thatPseudoplophophorus spp. and Plohophorus spp. share several potential synapomorphies with Phl.ameghini and St. compressidens, (late Miocene-Pliocene of Northwestern Argentina). If thishypothesis is confirmed, the tribe Plohophorini, could be interpreted as a natural group containingtwo radiations, one with eastern distribution (Argentina and Uruguay) and the other restricted to thewestern region (Argentina).