News Paleontology

Dinosaur handprints reveal birdlike arm anatomy

Inward-facing palms evolved much earlier than previously recognized

By Sid Perkins

- More than 2 years ago

Fossil handprints made by a crouching theropod reveal that those meat-eating bipedal dinosaurs had palms that always faced inward, a sign that these creatures abandoned the use of their forelimbs as legs early in their evolution.

TAKING A BREAK DINOSAUR HANDS. The handprints (arrows, left) presumed to be made by a resting theropod indicate that the creature couldn’t rotate its palm face down.