New Palaeogene cingulates (Mammalia, Xenarthra) from Santa Rosa, Perú and their importance in the context of South American faunas

Abstract

The record of Palaeogene cingulate xenarthrans in low latitudes is very poor. The cingulate fauna from the Yurúa River near Santa Rosa in eastern Perú is important because it is one of the oldest known from the Palaeogene of Perú and because of its tropical latitudinal position. Although remains are scarce, we recognize three new taxa: two species of Astegotheriini (Dasypodidae); Parastegosimpsonia peruana gen. et sp. nov., of small size, related to Eocene species from Patagonia; and another new species, ?Parastegosimpsonia sp. nov., which consists of an incomplete osteoderm representing the largest species of this tribe. A third species, Yuruatherium tropicalis gen. et sp. nov., of indeterminate suprageneric rank, shares features with Machlydotherium Ameghino (Casamayoran-Tinguirirican SALMA – middle Eocene-early Oligocene of Patagonia) and is similar to Eocoleophorus Oliveira et al. (Deseadan SALMA – late Oligocene of Brazil). We assign ?Machlydotherium intortum Ameghino (from the late Eocene of Patagonia) to Yuruatherium. Sediments bearing these cingulates also yielded rodents, marsupials and notoungulates, among the most frequent mammals. The absolute age of the sediments is unknown but an estimated age is inferred from studies of the mammalian assemblages. The age of the Santa Rosa local fauna is still controversial and given the groups taken into account, could be from Early Eocene to Late Oligocene. According to sequences of southern cingulate faunas (especially those of Dasypodidae), the cingulates from Santa Rosa also suggest an age between the Late Eocene and Early Oligocene. Nevertheless, the very low latitude of the Santa Rosa local fauna should be taken into account because in lower latitudes it is not uncommon to find taxa with a more generalized set of characters than those present in contemporary taxa from higher latitudes.

http://zoobank.org/urn:lsid:zoobank.org:pub:37CAEF7C-3CCC-4C3C-9869-D584FD73323C

Keywords:

• Cingulata
• Palaeogene
• Astegotheriini
• low latitudes
• diversity
• Perú, Amazonia

Acknowledgements

This study was greatly facilitated by access to specimens at the MLP (courtesy of M. Reguero), MACN (courtesy of A. Kramarz), LIEB-PV (courtesy of M. Tejedor), MPEF (courtesy E. Ruigómez) and LACM (courtesy of S. A. McLeod). We acknowledge Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) of Argentina. We thank J. Gonzalez for illustrations, and Dr F. J. Goin, an anonymous review and the Associate Editor for their valuable suggestions which improved the manuscript. This research was supported by the Agencia Nacional de Investigaciones Científicas y Técnicas (MINCYT, Argentina; PICT 1860) and Universidad Nacional de La Plata (UNLP-FCNYM N-593) to A.A.C.