The plesiadapiforms take to the trees
Squirrel-like archaic primates diversify across the northern forests and slowly assemble the primate body.
- When
- —
- Duration
- 9 million years
- Known to
- ± 1 million years
- Era
- Paleocene, Cenozoic
Plesiadapiforms are the dominant arboreal mammals of the Paleocene northern hemisphere, with dozens of genera across North America and Europe. They look more like squirrels than monkeys and most retain claws rather than nails, but they progressively acquire the traits that define primates: grasping extremities, mobile joints, and increasingly forward-facing orbits. Whether to call them primates has been argued for a century. Either way, they show that the primate package was assembled piece by piece rather than arriving whole.