Nothrotheriops sp. (Mammalia, Xenarthra) from the Late Pleistocene of Argentina: implications for the dispersion of ground sloths during the Great American Biotic Interchange

BRANDONI, D.; VEZZOSI, R.I.

BOREAS

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019

0300-9483

The aim of this contribution is to report and describe a femur (MCRS 199) assigned to Nothtrotheriops sp. from the Late Pleistocene of Santa Fe Province (Argentina), and discuss the implications of this find in the context of the dispersal of ground sloths during the Great American Biotic Interchange. The specimen MCRS 199 is smaller than the femora referred to the North American species Nothrotheriops texanus and Nothrotheriops shastensis but shares several features with these species: i) shape and position of the greater trochanter, ii) development of the lesser trochanter, iii) presence of connection between the third trochanter and the ectepicondyle, iv) distal third of the femur wider, with ML/DW index of 1.93, and v) location and relationship of the distal condyles. These similarities allow us to assign MCRS 199 to Nothrotheriops sp. The record of Nothrotheriops sp. from Santa Fe Province chronologically coincides with the earliest records of Nothrotheriops shastensis suggesting a broad geographic distribution of Nothrotheriops during the Late Pleistocene, ranging from 33°?36°N (e.g. California and Arizona States, USA) to 31°S (Northern Salado River, Santa Fe Province, Argentina). Thus, Nothrotheriops have dispersed from North America (where Nothrotheriops has early records, Calabrian?Middle Pleistocene) to South America where localities bearing Nothrotheriops are Late Pleistocene in age. In addition, once in South America and probably during the Middle Pleistocene, Nothrotheriops would gave rise to its sister taxa Nothrotherium, with records from the Middle Pleistocene (e.g. 223 ka BP, northeastern of Brazil) to the Late Pleistocene (e.g. 15 ka BP).