A tiny fossilized molar found nestled in the sweltering shrub land of Kenya’s Tugen Hills belonged to what may be the smallest species of ape yet discovered, a study said. The newly identified extinct species, Simiolus minutus, weighed only about 8 pounds.

Dwarfed by today’s gorillas, chimpanzees and orangutans, the miniature ape was possibly a casualty of natural selection, unable to compete with colobine monkeys that dined on the same leaves in trees 12.5 million years ago.

“They were trying to do what colobines were doing, which was foolish because no one had that same equipment,” said James Rossie, a paleoprimatologist at Stony Brook University in New York. “They brought a knife to a gunfight and then found out the knife was a plastic picnic knife.”

Rossie found the tooth in 2004 with a colleague, Andrew Hill from Yale University. Their finding provides insight into one aspect of an arms race between ancient apes and monkeys during the mid-to-late Miocene epoch 6 million to 14 million years ago.

Before then, ape species dominated the landscape. For some reason during this window, ape diversity crashed and the number of monkey species exploded.

The reason so many apes, including the small-body apes like Simiolus, disappeared is not clear. The prevailing hypotheses are that they died out because of competition from monkeys and environmental changes. Echoes from whatever happened during that period are still felt today as there are only about 20 species of apes, in contrast with more than 130 species of Old World monkeys in Africa and Asia.

New York Times