PITY the mammals living on lush Caribbean islands. Over the last 12,000 years, they have suffered the highest extinction rates of any on Earth. Now, a primate skull found in an underwater cave on Hispaniola underscores what we have lost 鈥� a fauna so primitive and strange that the archipelago has been likened to Madagascar.
Today, there are no primates in the Caribbean, and it wasn鈥檛 until 1952 that palaeontologists accepted that the islands had once been home to monkeys.
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The new find 鈥� the first well-preserved skull from Hispaniola (see picture) 鈥� confirms that this monkey was related to a group of primates still found in Central and South America that includes capuchins and squirrel monkeys. But although the skull is only a few thousand years old 鈥� too young to be called a fossil 鈥� the rear of its braincase is unlike that of any modern monkey. Instead, it most resembles a monkey that lived 16 million years ago in modern-day Argentina (, DOI: 10.1098/rspb.2010.1249).
Such 鈥渦ndercurrents of primitiveness鈥� in a recently extinct monkey suggest parallels with Madagascar, says at the City University of New York, whose team described the new skull.
惭补诲补驳补蝉肠补谤鈥檚 lemurs belong to the strepsirrhines, a group of primates now relatively rare in Africa. Just as they reveal what the archaic strepsirrhines of Africa would have looked like long ago, the recently extinct Hispaniola monkey (Antillothrix) could be a window onto South America鈥檚 ancient monkey fauna, says Rosenberger.
Because they have been isolated from mainland Africa for so long, many of 惭补诲补驳补蝉肠补谤鈥檚 primates have famously evolved bizarre features. Rosenberger says that the same is true of the Caribbean鈥檚 lost monkeys. The extinct Jamaican monkey (Xenothrix), for instance, can 鈥渓oosely鈥� be compared to the Aye-aye, a peculiar Madagascan primate with rodent-like incisors and a long finger for extracting insects from beneath bark.
And the limbs of the Cuban monkey (Paralouatta) suggest it spent at least part of its life on the ground, not in the canopy, says Rosenberger 鈥� something no living New World monkey does.
at the American Museum of Natural History, New York, says the Hispaniola skull is an important discovery. He used to think that a single monkey species, likely an ancestor of modern Titis, reached the Caribbean by chance, giving rise to all of the region鈥檚 monkeys. The morphology of the new skull doesn鈥檛 support this scenario, so he now agrees several species crossed the ocean to reach the Caribbean from South America.
In fact, he has geological evidence to suggest that around 33 to 35 million years ago, a thin land bridge called Gaarlandia would have offered ancient primates a dry route into the region (see map, right). If so, then the monkeys arrived in the Caribbean 10 million years earlier than the oldest fossils yet found.
When this article was first posted, the first sentence of the sixth paragraph read: 鈥淏ecause they have been isolated from mainland Africa for so long, many of 惭补诲补驳补蝉肠补谤鈥檚 monkeys have famously evolved bizarre features.鈥�
