Dinosaur-era bird tracks: Proof of 100-million-year-old flight?

It's all about the fourth toe. While birds and dinosaurs both left three-toed footprints, few dinosaurs have the backward-facing fourth toe that birds use to grab a branch or provide drag during landing. So when Anthony Martin saw the four-toed impression left in an Australian rock more than 100 million years old, he knew he was looking at something special.

"The track seemed familiar, like a face I had seen before but couldn’t quite identify," writes the Emory University paleontologist in a blog describing the find. "Then I realized who it belonged to, and where I had seen many others like it. It was a bird track, remarkably similar to those in the sands and muds of the Georgia coast, made daily by the herons, egrets, and shorebirds."

Source: Here