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, according to a new study. The newly identified extinct species, Simiolus minutus, weighed only about 8 pounds, or slightly less than an average house cat.

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 some 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, referring to the monkeys’ digestive abilities. “They brought a knife to a gunfight and then found out the knife was a plastic picnic knife.”

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