New species of the ground sloth Parocnus from the late Pleistocene-early Holocene of Hispaniola

Abstract

Parocnus dominicanus sp. nov. represents a new species of megalonychid ground sloth from theAltagracia Province of southeastern Dominican Republic. Specimens of multiple individuals, including oneassociated partial skeleton, were recovered from two separate underwater caves in the Parque Nacional delEste through collaborations with museums and cave divers between 2009–2013. Parocnus dominicanus sp.nov. is distinguished by its small size compared to that of P. serus, with percent differences in limb elementlengths ranging from 13−24%. Numerous cranial and post-cranial elements also exhibit morphological characterstates that are not attributable to size variations. The recovery of multiple individuals within each localitydemonstrates a size dimorphism, possibly sexual, which parallels patterns exhibited by P. serus. The twospecies are also geographically distinct, with no examples of co-occurrence at any localities to date. Parocnusdominicanus sp. nov. and P. serus share character states that are distinct from those of the Cuban species, P.browni, and which suggest differential usage of the forelimb. The exact age of the specimens described here isunknown, however, Parocnus has been dated to the Holocene in Haiti.http://zoobank.org/urn:lsid:zoobank.org:pub:12E495D3-E261-4522-9854-D3B4C2D5FFB8

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

“…Closely related to Megalocnus is Parocnus with three species, P. serus (Figure 4B) from Haiti, P. browni in Cuba, and P. dominicanus from the Dominican Republic [78,80]. The size varies among the three species and body mass estimates based on femur length are 79, 42, and 32 kg, respectively.…”

“…All Caribbean sloths are members of the Megalonychidae and are represented by four genera and multiple species. The most recent review of the taxonomic diversity is White and MacPhee [78], but subsequently to that review, additional species have been proposed [79,80]. While the body mass of the Caribbean sloths is significantly smaller than their mainland counterparts, many of the species are significantly larger than those of the next largest mammalian group, rodents, so the sloths constitute the "mammalian megafauna" on these islands.…”

“…The largest genus is Megalocnus with two species, M. rodens (Figure 4A) in Cuba and what was originally described as M. zile from Haiti. Megalocnus zile is now considered a junior synonym of Parocnus serus [80]. The Cuban record of the genus is extensive, and it has been recovered from multiple caves and from spring deposits, in contrast to M. zile which is only known from the holotype.…”

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

“…Acratocnus would have shared Hispaniola at this time with two other undoubted sloth genera. The largest, Parocnus , was a pig‐sized, ground‐dwelling sloth (McAfee et al, 2021; McAfee & Beery, 2019) . Acratocnus itself was larger than modern tree sloths, and likely semi‐arboreal.…”