If members of Archicebus achilles were alive today, they would fit in the palm of your hand. But the little creatures lived 55 million years ago. In June, paleomammalogist Xijun Ni and his team presented the new species. “Archie,” as it’s dubbed by some, is the oldest primate skeleton to date.
Found in China, Archie is very close to a common ancestor of humans, monkeys and the big-eyed, nocturnal South Asian tarsiers. To discover Archie’s place in the primate family tree, the research team spent 10 years developing and using the world’s largest phylogenetic data matrix. This system to analyze evolution allowed them to compare the skeleton’s characteristics with 1,844 features of other primates and their relatives.
The extensive analysis of a near-complete skeleton provides a detailed view into Archie’s varied traits. Its monkey-like feet and heels — for which the new species is named — and its tarsier-like hip and knee indicate that it leaped through the forest and crept along branches.
Its pointy teeth were, like those of tarsiers,used for chomping on insects. The skeleton suggests complex locomotion.
Archie’s relatively small eyes support Ni’s theory that the yet-to-be-discovered ancestor of our branch of primates was, like humans, active during the day, or diurnal.
[This article originally appeared in print as "Oldest Primate Finds Its Place on the Tree."]