Article: Megatherium celendinense sp. nov. from the Pleistocene of the Peruvian Andes and the phylogenetic relationships of megatheriines
A new Pleistocene megatheriine, Megatherium celendinense sp. nov., is reported from a cave in the north of the Peruvian Andes. It is the largest Andean Megatheriinae and is characterized by a short, massive, Y-shaped premaxilla unfused to the maxilla, a dorsoventrally compressed occiput perpendicular to the dorsal plane of the cranial roof, prominent and posteriorly extended occipital condyles, an extremely reduced deltopectoral crest and a poorly marked musculospiral groove on the humerus, a rectilinear anterior margin of the distal epiphysis of the tibia, a concave lateral margin of the fibula, discoid and ectal facets of the astragalus clearly separated in dorsolateral view, and a pedestaled articular facet for the meso-entocuneiform on the ectocuneiform. The monophyly of the subfamily is confirmed. (Pyramiodontherium, Megatheriops, Megatherium and Eremotherium) constitute a monophyletic clade and (Pyramiodontherium, Megatheriops) and (Eremotherium, Megatherium) are sister groups. The genus Megatherium includes two clades: (M. altiplanicum, M. americanum), subgenus Megatherium, and an Andean lineage (M. sundti, M. urbinai, M. celendinense sp. nov., M. tarijense, M. medinae), subgenus Pseudomegatherium. Anatomical characters suggest a more quadrupedal stance for Andean Megatheriinae (Ecuador, Peru, Bolivia and Chile) than those from lower altitude regions.