Species: Xenothrix mcgregori
Xenothrix mcgregori is a subfossil species discovered in Jamaica in 1919, although the species description was not completed until 1952. The find, apparently, consisted of a small mandible, femur, pelvis and tibia.
I couldn’t find any pictures of Xenothrix so a verbal description will have to suffice. The mandible lacks a third molar, as in living Callitrichidae, but unlike the Callitrichidae the second molars are bunodont and the canine is reduced. The mandible itself is large and stout and deepens posteriorly. The postcranial material is described as short and robust. Based on the available evidence it is thought that Xenothrix primarily ate fruit and was a slow moving quadruped. Xenothrix may have survived until the 18th century. The exact taxonomic placement of Xenothrix is still somewhat controversial.