SciTechDaily has a story that highlights a new dinosaur discovery that might rewrite the evolution of flight.  New research by a team led by James Napoli, from the Department of Anatomical Sciences in the Renaissance School of Medicine at Stony Brook University, found that some theropod dinosaurs had a bird-like carpal bone, or pisiform.  The existance of this write bone might shift views on how flight evolved.  The research was published in the journal Nature.

For a long time, scientists were uncertain about the identity of a particular carpal bone in the bird wrist, until it was confirmed to be the pisiform. Originally a sesamoid bone, similar in nature to a kneecap, the pisiform had shifted from its initial location in the wrist to take the place of another carpal bone known as the ulnare. In living birds, this new position helps form a joint system that enables the wing to fold automatically when the elbow bends.

The pisiform’s distinctive V-shaped notch also plays a structural role, helping it grip the hand bones securely and prevent dislocation during flight. As a result, the pisiform is a key component of the bird forelimb and is vital for effective flight mechanics.

The dinosaur fossils examined in this study included a troodontid, a bird-like predator related to the Velociraptor, and an oviraptorid, an unusual omnivorous dinosaur with a long neck and a beak but no teeth.