Early Jurassic Birds Couldn't Fly But They Did Glide, According to A New Study

Early Jurassic birds used feathers as insulation rather than full-fledged wings, according to a recent study published in Current Biology.

In an interview with Discovery News, Paleontologist Nicholas Longrich of Yale University asserts that the earliest birds, Anchiornis and Epidexipteryx, were not expert flyers.

"We don't think these things could take off the ground. They can't fly like a modern bird," he says. Anchiornis, which existed 155 million years ago, and Epidexipteryx, which lived from 152 million to 168 million years ago, were limited to gliding from trees.  

"Modern birds have the ability to separate their wing feathers sort of like a Venetian blind. This allows them to raise the wing rapidly, and seems to be critical to flapping flight at low speeds," said Longrich. "The feather arrangement in Archaeopteryx and Anchiornis wouldn't let them do this, so it may have made takeoff from the ground and flapping at low speeds more difficult."

The research suggest that birds found refuge from predators by nesting in trees, where they had a prime vantage point to spot prey.

The paleontologist notes, "Gliding is a fast way to move from tree-to-tree. Instead of climbing down one tree and running up the next, you just glide quickly from one to the other."

Speaking on evolution, Longrich states, "Where dinosaurs end and birds begin is a bit arbitrary. There's no clear cutoff that separates one from the other. That's the nature of evolution; things gradually change from one thing into another."

He adds, "Birds hit on a workable design about 130 million years ago, and it's been difficult to improve upon it."