The genus Patriarchus Ameghino, 1889 (Mammalia, Notoungulata, Typotheria), from the Santa Cruz Formation, Santa Cruz Province, Argentina

Abstract

In 1889, FlorentinoAmeghino erected Patriarchus palmidens, based on a specimen from a westernoutcrop of the Santa Cruz Formation (early Miocene), and associated it with the?Notohippidian? stage. Later, Ameghino added other seven species to the genus,from eastern localities of the same formation. Since 1900, Patriarchus has been traditionally considered as the junior synonymof Protypotherium. Here, we present asystematic revision and recognise the genus Patriarchusas monospecific, with Pa. palmidens, characterisedby: i1?c mesiodistally expanded,labially convex and similar in size; i1?c with a short lingual sulcus that doesnot extend to the base of the teeth, and V-shaped in occlusal view; p1 labialand lingually bilobated, with trigonid larger than talonid; and i1?p1 in acontinuous series without overlapping. Five of the remaining species are recognised as belongingto Protypotherium. Therefore, Patriarchus is presently monospecific (Pa.palmidens) and restricted to the westernregion of Santa Cruz Province, particularly to Río Bote locality. Patriarchus is included for the firsttime in a cladistic analysis in order to know its phylogenetic relationshipswithin the Interatheriidae. It is nested within the most derived Interatheriinae and isrecovered as the sister group of the Laventan Miocochilius; this clade is, in turn, the sister group of Cochilius plus Interatherium. These results support the hypothesis concerning theorigin of the Miocene Interatheriines in a single evolutionary event.