The analysis of recently recovered ground sloth remains from Minas Gerais, Bahia, and Piauí (Brazil) results in a major reinterpretation of the Scelidotheriinae and Megalonychidae of tropical Brazil. Among the specimens collected from Lagoa Santa (Minas Gerais) by Lund during the first half of the 19th century are skeletal elements attributable to two scelidotheriine species, as Lund himself determined and Winge corroborated. This is in contrast to the interpretation of these remains as representing a scelidotheriine and the postcranial remains of a peculiar megalonychid, as most authors, following Hoffstetter, have believed. A new combination is proposed here for one of the species. Another scelidotheriine recently described from Piauí by Guérin and Faure is a synonym of this species.