Encyclopedia of Islands

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Antillean Sloths and Primates

Antillean Sloths

The second largest adaptive radiation of land mammals in the Antilles occurred on Hispaniola (four genera and six species) and Cuba (five genera and six species), where sloths filled a number of niches. They ranged in mass from the size of a very large dog to smaller than a house cat (the smallest known sloth). The radiations of sloths on Cuba and Hispaniola were remarkably similar to each other.

Sloths are also known to have occurred on Puerto Rico (one named form and one unnamed form). This distribution confirms the close biogeographic affinity of these three islands. Sloths are not known to have occurred on Jamaica. Fragmentary dental remains of what is clearly sloth material are known from Grenada in the Lesser Antilles.  

Antillean Sloths

 No sloths have survived in the Antilles into historical times. Two large, ground-dwelling (i.e., mega-faunal) sloths were present on Hispaniola, and they were likely hunted to extinction by early Amerindians. Both are closely related to the giant megalonychid ground sloth from Cuba (Megalocnus rodens), estimated to have weighed 270 kg. Another part of the sloth radiation on Hispaniola and Cuba (subfamily Choloepodinae, tribe Acratocnini) are forms similar to the two-toed sloth (Choloepis) from Central and South America. These much smaller sloths, such as “Yesterday’s Acratocnus” (Acratocnus ye) are known from well-forested and savanna upland habitats in the southwest. It is likely that this form hung from branches as two-toed sloths do. Hispaniola also had three species of a smaller sloth group (tribe Cubanocnini). The larger form was the “Hispaniolan Neocnus” (Neocnus comes), which was widespread on Hispaniola. Also present on Hispaniola was the “Slow Neocnus” (Neocnus dousman) and the “Least Neocnus” (Neocnus toupiti). All three forms were excellent climbers and moved easily in the treetops but did not hang under branches (according to sloth expert Jennifer White).

Why and when the extensive radiation of sloths became extinct, in spite of their wide range of size, food habits, and locomotor habits, is not yet resolved. The well-preserved remains of sloths are common in sinkholes along the karst-covered plateaus of the southern peninsula of Haiti. These plateaus were well forested and probably represented the last haunts of sloths on the island. It is likely that they became extinct within the last 2000 years as a result of human activity.

Antillean Primates

Monkeys were first documented in the Antilles as an endemic platyrrhine (Antillothrix bernensis) in Hispaniola. Fossil endemic monkeys are also known from Cuba (Paraloutta varonai) and Jamaica (Xenothrix mcgregori). Fossil evidence of monkeys in the Greater Antilles extends back as far as the Early Miocene. The Hispaniolan monkey is similar to a living squirrel monkey (Saimiri). It was originally described as Saimiri bernensis but is now considered to be an endemic genus closely related to the Cuban monkey. The extinction of monkeys in the Greater Antilles was again probably the result of overhunting and deforestation by Amerindians.