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

ABSTRACT

In 1889, Florentino Ameghino erected Patriarchus palmidens, based on a specimen from a western outcrop of the Santa Cruz Formation (early Miocene) and associated it with the ‘Notohippidian stage’. Later, Ameghino added seven other species to the genus from eastern localities of the same formation. Since 1900, Patriarchus has been considered to be a junior synonym of Protypotherium. Here, we present a systematic revision and recognize the genus Patriarchus as monospecific, with Pa. palmidens characterized by i1–c mesiodistally expanded, labially convex, and similar in size; i1–c with a short lingual sulcus that does not extend to the base of the teeth and ‘V’-shaped in occlusal view; p1 labially and lingually bilobate, with trigonid larger than talonid; and i1–p1 in a continuous series without overlapping. Five of the remaining species are recognized as belonging to Protypotherium. Therefore, Patriarchus is presently monospecific (Pa. palmidens) and restricted to the western region of Santa Cruz Province, particularly to the Río Bote locality. Patriarchus is included for the first time in a cladistic analysis to discover its phylogenetic relationships within the Interatheriidae. It is nested within the most derived Interatheriinae and is recovered 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 that the origin of the Miocene Interatheriines was a single evolutionary event.

ACKNOWLEDGMENTS

We thank the editorial staff and the reviewers (D. Croft and M. Reguero) for their useful comments on the manuscript. We are grateful to the curators L. Chornogubsky (MACN), M. Ezcurra (MACN), A. Kramarz (former curator, MACN), D. Rubilar (SGO), and M. Reguero (MLP) for making available the collections under their care; Tecs. G. Aguirrezabala (MACN) and M. Miñana (MACN) for the preparation of several materials; and S. M. Alvarez for her help and goodwill during her time working at the MACN. We also thank S. Vizcaíno for providing the photographs of Scott’s catalog, and M. Bond for his constant willingness to share his knowledge on systematics and typotheres and to clarify any doubt or curiosity. We are indebted to those who promoted the field work in Santa Cruz, especially S. F. Vizcaíno and M. S. Bargo, and every person involved in successive field seasons. This is a contribution to projects ANPCyT-PICT 0389, PICT 2013-0389, and UNLP N/867. Finally, this work was partially supported by Universidad Nacional de Luján, grant CBLUJ 0000030-18 to J. C. Fernicola.