Purgatorius, at the root of the primates
A small climbing mammal from Montana, found in rocks straddling the boundary, sits near the primate origin.
- When
- —
- Duration
- 3 million years
- Known to
- ± 1 million years
- Era
- Paleocene, Cenozoic
Purgatorius is known mostly from teeth and a few ankle bones recovered from Hell Creek and immediately overlying beds in Montana, some possibly from the last stretch of the Cretaceous itself. The ankles are the important part: their mobile joints indicate a life spent in trees rather than on the ground, which pushes arboreality — the defining primate commitment — right back to the beginning. Whether Purgatorius is a true primate or a close relative depends on where the line is drawn, but the lineage it belongs to leads to us.