Imagine wandering around the Greater Antilles on an anole hunt with monkeys bouncing among the trees above. As it turns out, your imagination wouldn’t need to take you back more than a few hundred years to make this vision a reality. The Jamaican monkey (Xenothrix macgregori) – which was described in 1952 by Ernest Williams (a.k.a. the godfather of Anolis biology) and Karl Koopman (a.k.a. the namesake of the Haitian endemic Anolis koopmani) – may have even survived to see the first European explorers.
A recent PNAS article describes the fifth species of extinct monkey endemic to the Greater Antilles (two are from Cuba, two from Hispaniola, and one from Jamaica; see map above for more details). A precise age for this fossil is unknown, but the available evidence is consistent with the Holocene. In their description of Toussaint’s island monkey (Insulacebus toussaintiana), Cooke et al. contribute new data to the long-standing debate about the origins and evolutionary implications of the West Indian primate fauna. Most students of Greater Antillean monkeys agree that they represented a relictual clade of primates that had long since disappeared from northern South America. Although their precise phylogenetic affinities are still being debated, the West Indian species seem to be most closely related to either the owl monkeys (Aotus) or the titi monkeys (Callicebus). Cooke et al. further suggest that the large size of the Greater Antillean primates relative to mainland relatives may have resulted from the island effect.
Whether the Greater Antillean monkeys resulted from in situ radiation or multiple independent colonizations from the mainland remains a matter of debate. The new species appears similar to the Jamaican monkey, but Cooke et al. are dubious of its affinities to the Cuban species (Paralouatta). Although their sampling is limited to just a handful of localities, Cooke et al. also suggest the possibility that the presence of distinct species in northern and southern Hispaniola might reflect isolation of intermittent isolation of Hispaniola’s paleo-islands through the late-Quaternary. The distinctness of Hispaniola’s north and south paleo-islands, is, of course, well known to students of anoles and other West Indian herps.
I wish those darned monkeys had stuck around because molecular genetic studies might have added considerable insight to our understanding of the origins of the West Indian fauna. (Not to mention the fact that their presence would have made the life of West Indian field biologists a little more exciting!)
While our knowledge of extinct Greater Antillean primates remains as fragmentary as the bones they left behind, these monkeys serve as an important reminder that the communities we see today are often very different from those that anoles experienced in the not so distant past.