2026/03/01 by François Pujos, Gerardo De Iuliis, Alberto Boscaini +5 · 1 voice · 1 citation
Earth and Planetary Sciences · Psychology · #Evolution and Paleontology Studies #Lineage (genetic) #Manus #Osteology #Paleontology and Evolutionary Biology #Phylogenetic tree #Pleistocene #Primate Behavior and Ecology #Skull #Sloth #Taxon #Xenarthra
paper · doi:10.1093/zoolinnean/zlag008
published in Zoological Journal of the Linnean Society 206(3) (Oxford University Press)
openalex publication_date 2026/03/01 · openalex created_date 2026/03/22 · openalex updated_date 2026/07/30
Abstract Xenarthrans are among the more iconic endemic groups of South American mammals. We present new specimens, including a nearly complete skull and two partial skeletons, of the giant mylodontid sloth Ocnotherium giganteum, a large quadrupedal herbivorous sloth from the Late Pleistocene of the intertropical region of Brazil. The comprehensive osteological description of O. giganteum provided here sheds light on a previously very poorly known member of the mammalian assemblage from the Pleistocene of the intertropical region of Brazil. For nearly 200 years the species was known from only three isolated teeth and has long been misunderstood. Although several features suggest affinities between O. giganteum and Lestodontinae, phylogenetic analysis places this species within Mylodontinae, and the taxon is characterized by 22 autapomorphies. Ocnotherium giganteum exhibits a distinctive dentition, featuring a first upper molariform that is strongly arched posteriorly, a long diastema between the second and third upper teeth, short and robust limbs with powerful muscles, a pentadactyl manus with three clawed digits, a pes with at least four digits, and dermal ossicles. Digital endocranial studies on Ocnotherium reveal that it was characterized by large olfactory bulbs, extensive cranial pneumatization, and a relatively small osseous labyrinth.