New records and diet reconstruction using dental microwear analysis for Neolicaphrium recens Frenguelli, 1921 (Litopterna, Proterotheriidae)

Andrea Corona,Martín Ubilla,Daniel Perea

doi:10.5027/andgeov46n1-3136

Abstract

Neolicaphrium recens is the only survivor proterotherid in the Quaternary of South America, of which few fossil records from Argentina, Uruguay and probably Brazil are known. In this paper we describe new cranial remains with teeth series of N. recens from Artigas Department, Uruguay (Sopas Formation, Late Pleistocene), and previously published remains were reinterpreted and assigned to N. recens. We performed a dental microwear study of the seven most complete adult specimens from Argentina and Uruguay. The dental facets of interest were molded with silicone dental impression; the moulds were filled with epoxy resin and observed in a stereomicroscope. The paracone of M2 and the protoconid of m2 were photographed and the images digitally processed and studied. The results showed a high relative percentage of pits (scars of soft plants) on scratches (grooved pattern caused by silicophytoliths of grasses), indicating that the analyzed specimens were browsers, and their diet probably included fleshy leaves, buds and stems of trees and shrubs. These new data are consistent with previous results of carbon and oxygen isotopes studies and with inferences based on the associated fauna of N. recens in Uruguay, indicating for the Sopas Formation open to semi open grassland with forested areas, resembling a savanna. This study suggests some woodland environments for all the range of geographical distribution of the taxon.

Highlights

The Litopterna Ameghino, 1889 is one of the native mammalian groups of South America with a wide distribution limited to this continent
In this paper we describe new cranial remains with teeth series of N. recens from Artigas Department, Uruguay (Sopas Formation, Late Pleistocene), and previously published remains were reinterpreted and assigned to N. recens
These new data are consistent with previous results of carbon and oxygen isotopes studies and with inferences based on the associated fauna of N. recens in Uruguay, indicating for the Sopas Formation open to semi open grassland with forested areas, resembling a savanna

Summary

Introduction

The Litopterna Ameghino, 1889 is one of the native mammalian groups of South America with a wide distribution limited to this continent. They are diverse ungulates that appear in the Early Paleocene, showing a great diversification until the Pliocene when they dramatically decline. They got extinct during the Late Pleistocene/Early Holocene (Prado et al, 2015). Despite the fact that Frenguelli (1921) described Neolicaphrium recens found in Pleistocene sediments from Argentina, at that time this family was believed extinct in the Pliocene. New findings in Uruguay (Perea et al, 1995) suggested the presence of Neolicaphrium recens in the Quaternary, later confirmed by more collected and reviewed material from north center Argentina, northern Uruguay and probably in southern Brazil (Tauber, 2000; Bond et al, 2001; Scherer et al, 2009; Vezzosi et al, 2009; Ubilla et al, 2011; Luna et al, 2015; Schmidt et al, 2016; Vezzosi, 2016; Gaudioso et al, 2017)

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