Subfossil platyrrhine tibia (primates: Callitrichidae) from Hispaniola: a possible further example of island gigantism

A distal right tibia described by G.S. Miller in 1929 (Smithsonian Misc. Coll. 82[5]:1-16) on the island of Hispaniola is shown to be that of a heretofore unknown extinct platyrrhine and is informally referred to as Ceboid M. Its affinities appear to be with the dwarfed callitrichids, especially Saguinus. It is suggested that Ceboid M represents yet another case of gigantism in the Antilles, in response to a lack of both competitors and predators. A reconsideration of the affinities of Xenothrix mcgregori from Jamaica is suggested.