New Cingulata (Mammalia, Xenarthra) from the late Neogene Palo Pintado Formation (Northwestern Argentina)

Abstract

Cingulata (Early Eocene-Recent) is a very well-diversified clade that reached a high diversity during the early Neogene. In southern South America, there is an evident imbalance in our knowledge of the Neogene diversity along the Northwestern region of Argentina (NWA) compared to the Pampean region (PR), despite the importance of NWA to understanding the hypothetical evolutionary scenarios of several clades. The Palo Pintado Formation (ca. 10–5 Ma) is one of the richest units in NWA, involving both the global warming of the Tortonian (ca. 11.6–7.25 Ma) and the global cooling event of the Messinian (ca. 7.25–5.33), coeval with the widespread of the C4 plants. Despite this, Cingulata from this Formation are still poorly known. Interdisciplinary fieldwork at Calchaqui Valley (Angastaco Basin) yielded several new remains, including Chlamyphoridae Euphractinae Proeuphractus limpidus, Chorobates villossisimus and Prozaedyus sp.; Dasypodidae Dasypus sp.; Pampatheriidae Kraglievichia paranensis; and Glyptodontidae Cranithlastus xibiensis. The “armadillos” P. limpidus, Prozaedyus sp., and Dasypus sp. increase the previously known diversity. The record of Dasypus sp. reinforces recent hypotheses extending the biochron of the genus to the Late Miocene in NWA. The recognized taxonomic diversity of glyptodonts, limited to one species, contrasts with that known from other coeval formations placed both in the south (Andalhuala and Corral Quemado formations, Catamarca Province) and the north (Maimará and Tafna formations, Jujuy Province), revealing a complex biogeographic scenario for this clade during this period. The analyzed deposits are interpreted as accumulated within the channel and formed during episodes of large discharges of water and sediment mostly under a warm subtropical climate, tough there is an aridization recorded at ca. 6 Ma, which is probably related to the increase in the taxonomic diversification of Cingulata along the stratigraphic sequence.