Cranial and dental studies of Glossotherium robustum (Owen, 1842) (Xenarthra: Pilosa: Mylodontidae) from the Pleistocene of southern Brazil

Abstract

Pitana, V.G., Esteban, G.I., Ribeiro, A.M. & Cartelle, C. 2013. Cranial and dental studies of Glossotherium robustum (Owen, 1842) (Xenarthra: Pilosa: Mylodontidae) from the Pleistocene of southern Brazil. Alcheringa, 1–16. ISSN 0311-5518. Mylodontine ground sloths were studied from several Pleistocene localities of Rio Grande do Sul State: São Gabriel (central region), Quaraí, Uruguaiana and Alegrete (western region) and Santa Vitória do Palmar (coastal region) municipalities. The cranial and mandibular material is assigned to Glossotherium robustum based on the enlargement of the anterior portion of the maxilla, a rounded and ventrolaterally arched fossa for the estylohyal, an elliptical occipital condyle, a spatulate symphyseal region of the mandible, together with the size and degree of lobulation of the teeth. Comparison with specimens from the Pampean region of Argentina, western Uruguay and northeastern Brazil revealed that the Rio Grande do Sul material is most similar morphologically to that of the Pampean region of Argentina and Uruguay. These southern specimens are morphologically distinct from Pleistocene material from tropical Brazil assigned to Glossotherium sp. The Pleistocene records of G. robustum indicate that this taxon was widely distributed between 20°S and 40°S spanning Argentina, Brazil, Bolivia, Chile, Uruguay and Paraguay, whereas Glossotherium sp. was restricted to latitudes <30°S.