The oldest known record of a ground sloth (Mammalia, Xenarthra, Folivora) from Hispaniola: evolutionary and paleobiogeographical implications

Abstract

Sloths were among the most diverse groups of land vertebrates that inhabited the Greater Antilles until their extinction in the middle-late Holocene following the arrival of humans to the islands. Although the fossil record of the group is well known from Quaternary deposits in Cuba, Hispaniola, and Puerto Rico, remains from older units are scarce, limiting our understanding of their evolution and biogeographic history. Here we report the oldest known fossil ground sloth from Hispaniola, represented by an unassociated partial tibia and scapula that are recognized as a single taxon from the late Miocene-early Pliocene of the Dominican Republic. The combination of characters observed on the tibia suggests a close relationship with Megalocnus, otherwise only known from the Pleistocene–Holocene of Cuba. These fossils fill a temporal gap between those previously known from the early Miocene of Cuba and those from Pleistocene–Holocene deposits in the region and provide additional support for a continuous presence of the group in the Greater Antilles since the Oligocene.

A Tale of Two Continents (and a Few Islands): Ecology and Distribution of Late Pleistocene Sloths

“…Of all the taxonomic groups originating in South America, the sloths were the best dispersers, reaching the Caribbean Islands in the middle Neogene prior to the formation of the Isthmus of Panama. All sloth taxa found on Caribbean Islands are members of the Megalonychidae and first appear in the early Miocene in Cuba [2], the late Miocene-early Pliocene in the Dominican Republic, on Hispaniola [3], and early Oligocene of Puerto Rico [2]. By the late Miocene, a megalonychid and a mylodontid are present in North America, again prior to the establishment of the Isthmus of Panama, and this was followed by later separate dispersals of sloths including nothrotheriid, megatheriids as well as additional megalonychids and mylodontids [4].…”

The inner ear of caviomorph rodents: Phylogenetic implications and application to extinct West Indian taxa

“…Nowadays, only two surviving threatened groups survive in the region: the solenodons (Solenodontidae, Eulipotyphla) and hutias (Capromyinae, Echimyidae, Octodontoidea, Caviomorpha, Rodentia). Extinct lineages of Antillean mammals are numerous, and include megalocnid sloths (e.g., MacPhee and Iturralde-Vinent 1994; Delsuc et al 2019;Presslee et al 2019;Viñola-López et al 2022a), platyrrhine primates (e.g., Ford 1990;MacPhee and Iturralde-Vinent 1994;Horovitz and MacPhee 1999;MacPhee and Horovitz 2004;Cooke et al 2011;Rosenberger 2011Rosenberger , 2013, eulipotyphlan insectivores (Nesophontidae and several Solenodontidae; e.g., Silva et al 2007;Morgan et al 2019;Buckley et al 2020), echimyid rodents (Heteropsomyinae and most Capromyinae; e.g., Anthony 1916;Miller 1916;Woods et al 2001;MacPhee 2009;Viñola-López et al 2022b), as well as the giant rodents that are one of the topic of this paper, and traditionally grouped as members of the paraphyletic family Heptaxodontidae (for a summary, see MacPhee 2011). Except for Capromyinae and Solenodontidae, most of these West Indian mammal lineages were recently extirpated (Morgan and Woods 1986;MacPhee 2009;Turvey et al 2017;Orihuela et al 2020;Viñola-López et al 2022b).…”

Cranial osteology of a juvenile specimen ofAcratocnus ye(Mammalia, Xenarthra, Folivora) and its ontogenetic and phylogenetic implications

“…Neocnus would have been smaller than Acratonus , similar in size or smaller than modern tree sloths and more arboreal than Acratocnus (MacPhee et al, 2000; Matthew & de Paula Couto, 1959; McAfee & Beery, 2019; McDonald & De Iuliis, 2008; White, 1993). Megalocnidae is estimated to have reached the Greater Antilles during the Oligocene, around 32 Ma, with the earliest definitive specimen, Imagocnus , coming from the early Miocene of Cuba (MacPhee & Iturralde‐Vinent, 1994; MacPhee et al, 2003; McDonald & De Iuliis, 2008—see also late Miocene records from Hispaniola; Viñola‐Lopez et al, 2021).…”