Sloths represent one of the most successful South American clades that reached North America during the Great American Biotic Interchange (GABI). At least four families are known from the Pleistocene of North America: Mylodontidae, Megalonychidae, Megatheriidae, and Nothrotheriidae. Members of the Nothrotheriidae are known from the Middle Miocene to the Pleistocene/Holocene transition in the Americas, but Nothrotheriops is the only genus in the family recorded in North America. Recently, femora with characteristic nothrothere morphology were recovered from Santa Fe, Argentina, and assigned to Nothrotheriops, thus greatly expanding the geographic distribution of this taxon. In Uruguay, records of Quaternary Nothrotheriidae are scarce, and previous reports are limited to the genus Nothrotherium. In this work, we describe a humerus from Arroyo del Vizcaíno (AdV), a ~30 ka site located in southern Uruguay, and assign it to the nothrotheriid Nothrotheriops sp. We also discuss several specimens from Uruguay originally assigned to Nothrotherium, which upon re-examination can be tentatively reassigned to Nothrotheriops sp. Furthermore, we employ stable isotope analysis to explore the climatic and dietary preferences of this taxon in South America. The new records are consistent with the materials reported from Argentina, thus providing new knowledge of the geographic distribution of the taxon, as well as its climatic and dietary preferences. Stable isotope results showed δ¹³C values consistent with diets based mainly on C₃ plants, similar to those published for N. shastensis in North America.

树懒是南美最成功的进化枝之一，它们在大美洲生物交流 (GABI) 期间到达北美。在北美的更新世，至少有四个科是已知的：Mylodontidae、Megalonychidae、Megatheriidae 和 Nothrotheriidae。Nothrotheriidae 的成员在美洲的中中新世到更新世/全新世过渡期间为人所知，但Nothrotheriops是该科中在北美记录的唯一属。最近，从阿根廷圣达菲发现了具有典型 nothrothere 形态的股骨，并将其归类为Nothrotheriops，从而大大扩展了该分类群的地理分布。在乌拉圭，第四纪野兽科的记录稀少，以往的报道仅限于该属野兽。在这项工作中，我们描述了来自 Arroyo del Vizcaíno (AdV) 的肱骨，这是一个位于乌拉圭南部的约 30 ka 遗址，并将其分配给 nothrotheriid Nothrotheriops sp。我们还讨论了几个来自乌拉圭的标本，这些标本最初被归类为Nothrotherium，经过重新检查可以暂时重新归类为Nothrotheriops sp。此外，我们采用稳定同位素分析来探索南美洲该分类群的气候和饮食偏好。新记录与阿根廷报告的材料一致，从而提供了有关该类群地理分布及其气候和饮食偏好的新知识。稳定同位素结果显示δ ¹³C 值与主要以 C ₃植物为基础的饮食一致，类似于北美为N. shastensis发布的那些值。