Carpolestes grasps a branch with a nail
A late Paleocene climber has an opposable big toe with a flat nail — but eyes still on the sides of its head.
- When
- Known to
- ± 500 thousand years
- Era
- Paleocene, Cenozoic
Carpolestes simpsoni, from Wyoming, has a divergent grasping big toe capped by a nail rather than a claw, the earliest such foot known. Crucially, it does not have forward-facing eyes. That combination separates two hypotheses that had been bundled together: grasping did not evolve to serve stereoscopic predation on insects, but for careful movement on slender branches, probably to reach flowers and fruit. Visual convergence came later. The hand that would eventually hold a tool starts as a device for not falling out of a tree.