The mylodontine ground slothGlossotherium tropicorumfrom the late Pleistocene of Ecuador and Peru

Abstract

New mylodontine (Xenarthra, Pilosa) sloth remains from the late Pleistocene tar seep localities of Corralito (Ecuador) and Talara (Peru) are described, and the taxonomic history of the extinct ground sloth genus Glossotherium is reviewed. Based on the new material and comparisons with Glossotherium robustum, Glossotherium wegneri, and the North American taxon, Paramylodon harlani, the species Glossotherium tropicorum is considered to be valid and a new definition of its diagnostic characters is provided. Glossotherium tropicorum is similar in size to Glossotherium robustum and Glossotherium wegneri but differs in several respects from these species, such as having a more elongated and slender skull. In this respect it more closely resembles Paramylodon harlani in North America, which is also similar in size. Glossotherium tropicorum is one of two mylodontine sloths found in the upper Pleistocene of north‐western South America, the other being Glossotherium wegneri. While both are present in this region their individual distributions did not overlap and the two species have not been recovered together in a fauna. The distribution of Glossotherium tropicorum is restricted to lowland coastal areas whereas Glossotherium wegneri is found inland and in the highland areas of the Andes, suggesting significant differences in their ecology.

Phylogenetic and functional implications of the ear region anatomy of Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina

“…Previous studies of the ear region in Glossotherium robustum, however, are either outdated or incomplete. The early descriptions by Owen (1842), van der Klaauw (1931) and Guth (1961) were pioneering works in their time, but suffered from erroneous taxonomic attribution (for a summary of the chaotic taxonomic history of the genus Glossotherium, see Esteban 1996;Fernicola et al 2009;McAfee 2009;De Iuliis et al 2017), as well as old terminology and a lack of detail. More recently, Patterson et al (1992) provided descriptions of the ear region in a wide variety of extinct and extant sloths, but only marginally considered the genus Glossotherium, whose description was coupled to that of the North American genus Paramylodon.…”

A reappraisal of the phylogeny of Mylodontidae (Mammalia, Xenarthra) and the divergence of mylodontine and lestodontine sloths

“…However, the close alliance of G. tropicorum and G. phoenesis is more reliable, since this relationship is recovered in all the analyses of the present study (Figures ). These two species have been recently reviewed by De Iuliis et al () and Cartelle et al () and joined in a monophyletic group by the latter study. Based on the results of the present analyses (Figures ), the rounded profile of the anterior edge of the mandibular symphysis is the only unambiguous synapomorphy for the node linking G. tropicorum and G. phoenesis .…”

“…Among them, Lestodontini (Figure : node O) appears with fully resolved internal relationships among the five genera included. In contrast, the only relationship that is consistently recovered among Mylodontini is the placement of Pleurolestodon acutidens (Argentina, late Miocene; Rovereto, ) as sister taxon to all the other Mylodontini (Figure : node S), and the monophyly of the group comprised of Glossotherium tropicorum (late Pleistocene of Venezuela, Peru and Ecuador; Bocquentin, ; De Iuliis, Cartelle, McDonald, & Pujos, ) and G. phoenesis (Figure : node U), as in Cartelle et al ().…”

New well-preserved materials ofGlossotherium chapadmalense(Xenarthra, Mylodontidae) from the Pliocene of Argentina shed light on the origin and evolution of the genus

“…In lateral view, the nasal region appears depressed in relation to the braincase (Figs. 2C, 3C), but to a lesser extent than observed in Glossotherium tropicorum (De Iuliis et al, 2017), G. phoenesis (Cartelle et al, 2019), Pleurolestodon acutidens (FMNH P14495), and Simomylodon uccasamamensis . The rostrum height of G. chapadmalense is almost at the level of the cranial roof, being in this regard similar to the conformation observed in G. robustum (Owen, 1842) and P. harlani (Stock, 1925).…”