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

Abstract

The aim of this contribution is to describe a femur (MCRS 199) assigned to Nothrotheriops 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 geographical distribution of Nothrotheriops during the Late Pleistocene, ranging from 33–36°N (e.g. states of California and Arizona, 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 probably gave rise to its sister taxon, Nothrotherium, with records from the Middle Pleistocene (e.g. 223 ka BP, northeastern Brazil) to the Late Pleistocene (e.g. 15 ka BP).

Osteología Craneana Y Taxonomía De Pronothrotherium (Xenarthra, Folivora, Nothrotheriidae) Del Mioceno Tardío–plioceno Temprano De La Provincia De Catamarca (Argentina)

“…and Nothrotheriops, North and central America, with a probable record in Argentina; McDonald & De Iuliis, 2008;Brandoni & Vezzosi, 2019). Craniodental remains of the Pleistocene taxa such as Nothrotherium and Nothrotheriops are fairly abundant.…”

Xenarthrans of the collection of Santiago Roth from the Pampean Region of Argentina (Pleistocene), in Zurich, Switzerland

“…maquinense (Lund, 1839 ) although Pujos ( 2001 ) considered the species to be valid. A revision of the taxonomic diversity of nothrotheres in the Pampean Region should be carried out (Brandoni & Vezzosi, 2019 ). PIMUZ A/V 477 follows perfectly the diagnosis of the genus proposed by Pujos ( 2001 ), with a small size, cylindrical and elongated cranium, distinct area for prominent pterygoid sinuses, globular parietal region higher than the frontal and exhibiting strong posterior inclination, absence of caniniform, anteroposteriorly narrow Mf4, that appear less quadrangular compared to the other teeth based on the tooth alveoli.…”

“…De Iuliis ( 1996 ) included a ground sloth specimen from the collection of Roth at PIMUZ in his revision of the systematics of the Megatheriinae. During the last 20 years, with the exception of a study on the histology and bone compactness of xenarthran long bones (Straehl et al, 2013 ), PIMUZ specimens from the collection of Roth were sporadically integrated into much larger datasets for the postcranial anatomical description of Eutatus Gervais, 1867 (Krmpotic et al, 2009 ), for the revision of the systematics of Scelidotheriinae based on cranial materials (Corona et al, 2013 ; Miño-Boilini, 2012 , 2016 ; Miño-Boilini & Quiñones, 2020 ; Miño-Boilini & Zurita, 2015 ; Miño-Boilini et al, 2014 ), for functional and ecomorphological studies using histology and microanatomy of several postcranial bones in mammals (Houssaye et al, 2016a ) and on a larger evolutionary level (Houssaye et al, 2016b ), and for the systematics of the Nothrotheriinae (Brandoni & Vezzosi, 2019 ; Vezzosi et al, 2019 ). It should be noted that since the work of Guth ( 1961 ), no study has incorporated glyptodonts from this collection, or even more broadly Cingulata with the exception of Krmpotic et al ( 2009 ).…”

A Patagonian swan (Anatidae: Anserinae) from the Upper Pleistocene of Austral Chaco (Argentina)

“…For the Upper Pleistocene of the austral Chaco region, several lithostratigraphic units from both principal fluvial basins are recognized, the Dulce and Northern Salado Rivers (Battaglia, 1982;Iriondo, 2010;Vezzosi et al, 2019). Some of these sequences are fossiliferous with aquatic and continental vertebrates (Frenguelli, 1920;1932;Castellanos, 1924;Vezzosi, 2016;Vallone et al, 2017;Gaudioso et al, 2017;Vezzosi et al, 2017;Albino & Gaudioso, 2018;Brandoni & Vezzosi, 2019;Gaudioso et al, 2019). Along the cut banks of the Dulce River the Tasigasta, Atamisqui and Dos de Mayo geological formations crop out, as well as other fluvial lithostratigraphic units such as the Capellanía Formation (Battaglia, 1982;Iriondo, 2010), that have reported continental Pleistocene vertebrate.…”