An international team of scientists has dated a species of a rare monkey — roughly the size of a small cat who lived largely on a diet of fruit and leaves — from the Caribbean region to just over one million-year old.

According to lead researcher Dr Helen Green from Melbourne University, the question of the age of primate fossils from this region has puzzled scientists since the days of famed naturalist Charles Darwin and biologist Alfred Russel Wallace.

“The presence of endemic new world monkeys on the Caribbean islands is one the great questions of bio-geography. By establishing the age of these fossils, we have changed the understanding of primate evolution in this region,” Dr Green said.

The discovery was made after the researchers recovered a fossil tibia (shin bone) belonging to the species of extinct monkey Antillothrix bernensis from an underwater cave in Altagracia Province in Dominican Republic.

The fossil was embedded in a limestone rock that was dated using the Uranium-series technique.

The team used 3D methods to confirm that the fossil tibia does indeed belong to Antillothrix bernensis - a primate that we now know existed on Hispaniola (located in the Caribbean island group called the Greater Antilles) relatively unchanged for over a million years.

This helped them to reconstruct how the small primate might have moved about in its environment and allowed the comparison of relatively young examples of Antillothrix bones to the newly discovered million year old specimens.

“Very little was known about the native monkey from this island,” added Dr Siobhan Cooke from Northeastern Illinois University.

The paper was published in the Journal of Human Evolution.