New record of Sphenotherus (Xenarthra, Mylodontidae) from the upper Tertiary of El Cajon valley (Catamarca province, Argentina).

The new material of Sphenotherus is from Huayquerian levels (late Miocene) in the northern part of El Cajon valley, Catamarca province (NW Argentina). This record extends the geographic distribution of the genus, and helps to define the diagnostic characters. The revised diagnosis includes the follo wing features: lower tooth rows laterally concave, lower caniniform lying o n the lingual side, and last lower molariform with a singular combination o f: characters. The two species included in this genus are: Sphenotherus zav aletianus Ameghino and Sphenotherus paranensis Ameghino. The latter has bee n characterized by having the posterior lower molariforms smaller than thos e of the former. However, this feature is considered not valid and thus S. paranensis is synonymized to S, zavaletianus.