A new genus and species of nothrotheriid sloth (Xenarthra, Tardigrada, Nothrotheriidae) from the Late Miocene (Huayquerian) of Peru

Abstract

The nothrotheriine sloth from riverbank deposits of the Río Acre region of Peru in western Amazonia was originally assigned to Nothropus priscus Burmeister, 1882. Although relatively complete, with essentially the pes unknown, its description was accompanied only by limited information on its cranial remains. The remains of this sloth, actually of late Miocene age, were extensively prepared. Subsequent analysis indicates that its original assignment is incorrect and that it belongs to a new genus and species, which is distinguished from other nothrotheriines by the following (among other) features: notably domed braincase; depressed, narrow snout; lack of parietal ⁄ alisphenoid contact; ulna with prominently projecting anconeal process; distal position of femoral greater trochanter; medial articular condyle of femur butts against patellar trochlea. Phylogenetic analysis places the new genus and species as sister group to the (Pronothrotherium (Nothrotheriops + Nothrotherium)) clade.

Osteology and Functional Morphology of the Hind Limb of the Marine Sloth Thalassocnus (Mammalia, Tardigrada)

“…A similarlylocated tuberosity is found in the mylodontid Lestodon Gervais, 1855, and other nothrotheriids. This morphology differs from that of Hapalops in which a lateral and a medial groove are present (De Iuliis et al 2011).…”

Revisión del perezoso terrestre Nothropus (Mammalia, Xenarthra, Tardigrada) del Pleistoceno de Argentina y Bolivia

“…Numerosos autores han utilizado el género Nothropus para realizar comparaciones con otros notroterinos (ver, entre otros, Pujos, 2001;Perea, 2007;De Iuliis et al, 2011;Brandoni, 2014;Brandoni & McDonald, 2015) o bien con otros grupos de perezosos terrestres (e.g. Megatherioidea, Pujos et al, 2011Pujos et al, , 2014.…”

A new genus of Megalonychidae (Mammalia, Xenarthra) from the Late Miocene of Argentina

“…Nothrotherium Lydekker, 1889, Nothropus Burmeister, 1882, Pronothrotherium Ameghino, 1907, Nothrotheriops Hoffstetter, 1954, Mionothropus De Iuliis, Gaudin & Vicars, 2011 or as basal Megatherioidea (e.g. Hapalops Ameghino, 1887, Schismotherium Ameghino, 1887, Xyophorus Ameghino, 1887, Pelecyodon Ameghino, 1891) (Gaudin, 2004;De Iuliis et al, 2011;Pujos et al, 2011).…”

“…presence of a relatively robust caniniform, presence of diastema between c1 and m1); however, the presence of apicobasal grooves on the lingual and vestibular surfaces of the molariforms (m1 and m2) it is not common among Megalonychidae, apicobasal grooves are present in the molariforms of some specimens of Neocnus (McAfee, 2011), but resembles the morphology of the molariforms of Nothrotheriidae (see De Iuliis et al, 2011). According to De Iuliis et al (2011), the presence of apicobasal grooves on molariform teeth is a synapomorphy of Nothrotheriidae (represented by Thalassocnus Muizon & McDonald, 1995, Mionothropus, Pronothrotherium, Nothrotherium, and Nothrotheriops in the analysis performed by De . In addition, this feature is also present in the Nothrotheriinae "Xyophorus" bondesioi Scillato-Yané, 1979, and "Xyophorus" villarroeli Saint-André, 1996(Brandoni, 2014.…”

“…In some Nothrotheriinae (e.g. Pronothrotherium typicum Ameghino, 1907, Mionothropus cartellei De Iuliis, Gaudin & Vicars, 2011) and some basal megatherioids (e.g. Hapalops), the caniniform is reduced, subcircular or suboval in outline, and separated from the molarifoms by a diastema.…”