Newly discovered fossilized bones for the world’s oldest and most primitive known primate, Purgatorius, reveal a tiny, agile animal that spent much of its time eating fruit and climbing trees, according to a study.

The fossils, described today in a presentation at the Society of Vertebrate Paleontology’s 72nd Annual Meeting in Raleigh, North Carolina, are the first known below-the-head bones for Purgatorius. Previously, only teeth revealed its existence. …

This mammal is generally believed to have been small and brown, and had a bushy tail. The researchers liken it to another early primate, Dryomomys, for which more fossil material is available. Based on that and the newly found bones, Purgatorius weighed about 1.3 ounces, making it roughly the size of the smallest living primates: the mouse lemurs of Madagascar.