The Million Year Old Monkey
In 2009 a remarkable find was made deep in an underwater cave in the Dominican Republic. A collection of beautifully preserved animal bones were recovered and now a closer examination of these finds is beginning to shed light on a long standing debate over one of the islands more enigmatic ex-inhabitants.
Antillothrix bernensis was a small bodied primate that went extinct sometime around the sixteenth century. It was around the size of a house cat and was native to the island of Hispaniola but little else was really known about this species because of its sparse fossil record. Then in 2009 divers at La Jeringa Cave in the Dominican Republic discovered a treasure trove of bones, including the first ever Antillothrix skull. This find radically altered our understanding of the evolution and family tree of this little monkey but now there has been another important breakthrough. Earlier this month (September 2015) an international team of scientists announced that they have successfully dated the bones recovered from the cave.
Antillothrix is one of several primate species once endemic to the Greater Antilles and how these monkeys were related to their mainland cousins has always been unclear. Knowing when their ancestors first arrived on the islands would give a good foundation for any theory though and it has previously been frustratingly difficult to get good dates. Fossils cannot be dated directly and so palaeontologists usually turn to the rocks they are buried in for clues. In this case a fragment of leg bone embedded in limestone offered the vital information. Firstly the researchers had to establish if the bone really did belong to a Antillothrix and to do this the team used specialist 3D modelling software to compare the shape of the bone to other, known fossils. Once this was established they used a combination of uranium-thorium and uranium-lead isotope dating to establish the age of the limestone. The date came back as around 1 million years which means that Antillothrix was present on Hispaniola during the last Ice Age. It was also possible, by comparing this fossil to more modern ones, to see that the species changed little physically over the millennia until it finally died out with the arrival of Europeans.
Rosenberger, A.L., et al. 2015. 1.32 ± 0.11 Ma age for underwater remains constrain antiquity and longevity of the Dominican primate Antillothrix bernensis. Journal of Human Evolution. DOI:10.1016/j.jhevol.2015.05.015
Featured Image: Credit the Journal of Human Evolution