Updated knowledge on the Notoungulata (Mammalia) from the late Miocene Cerro Azul Formation, La Pampa Province, Argentina

SOSTILLO, R.; MONTALVO, C.I.; CERDEÑO, E; SCHMIDT, G.I.; FOLGUERA, A.; CARDONATTO, M.C.

Historical Biology

Taylor & Francis

Año: 2019

We describe new remains of notoungulates from the Cerro Azul Formation (lateMiocene) in La Pampa Province and reassign others previously studied, helping to precisethe taxonomic diversity of 25 fossiliferous localities of this formation. Geomorphologicalcontext previously described for the area provides data to place some localities in atemporal sequence. The following Notoungulata are recognized: Protypotherium minutum(Interatheriidae), Paedotherium minor, Tremacyllus impressus, Hemihegetotheriumachataleptum, H. torresi, and Hemihegetotherium sp. (Hegetotheriidae), Typotheriopsissilveyrai, T. chasicoensis, and Pseudotypotherium subinsigne (Mesotheriidae), andPisanodon nazari, Hemixotodon chasicoensis, and cf. Stenotephanos plicidens(Toxodontidae). This study allows adding new localities to the biochronological sequencepreviously proposed based on the evolutionary pattern of the octodontoid rodents.Chasicoan and early Huayquerian (as herein considered) faunal assemblages present higherdiversity of notoungulates than those assigned to late Huayquerian. Some localities lack arepresentation of taxa significant enough to precise their biochronological position withinthe late Miocene. The difference in the notoungulates representation along the Chasicoan?Huayquerian ages may be due to climatic changes that affected the center of Argentinafrom late Miocene to early Pliocene.