The Late Miocene mammals from the Humahuaca Basin (northwestern Argentina) provide new evidence on the initial stages of the Great American Biotic Interchange

CANDELA, ADRIANA M.; ABELLO, MARÍA A.; REGUERO, MARCELO A.; GARCÍA ESPONDA, CÉSAR M.; PARDIÑAS, ULYSES F.J.; ZURITA, ALFREDO A.; PUJOS, FRANCOIS; MIÑO?BOILINI, ÁNGEL; QUIÑONES, SOFÍA; GALLI, CLAUDIA I.; LUNA, CARLOS; VOGLINO, DAMIÁN; DE LOS REYES, MARTÍN; CUARANTA, PEDRO

Papers in Palaeontology

The Palaeontological Association

Año: 2023 vol. 9

2056-2799

We describe new Late Miocene mammalianspecimens from the Maimara Formation (Late Miocene toEarly Pliocene) exposed at Humahuaca Basin (23°–24°S),northwestern Argentina (NWA), and analyse their taxonomyand relevance for our understanding of the initial stages ofthe Great American Biotic Interchange (GABI). The stratigraphicaland geochronological control of the studied specimensindicates a time window of c. 6.6–5.8 Ma. These dataare crucial for establishing the oldest records of the Holarcticimmigrants of the GABI. The first record of cricetid rodentsfrom the Maimara Formation is reported. Moreover, with anage of c. 6 Ma it is the first appearance datum (FAD) ofthese rodents in South America. The age of the procyonidCyonasua recorded in this unit is estimated between c. 6.6and c. 6.4 Ma. The record of procyonids and cricetids in thesame continuous sedimentary sequence suggests that thetime interval between the dispersion of both groups into thecontinent during GABI was c. 1 myr. Of the autochthonousmammals from the Maimara Formation, the first records oflitopterns, chlamyphorid and mylodontine xenarthrans, andcaviomorph rodents (including new species Pithanotomys?solisae and Palaeocavia humahuaquense) are described. FADsof immigrant and autochthonous mammals in NWA suggesta major faunal turnover during GABI at the Messinian,probably linked to global climatic changes and the tectonicactivity that affected the Humahuaca Basin at that time.Hypsodonty, a dominant feature among Maimaran mammals,may be related to a landscape strongly influenced bythe Andean uplift.