The book on the evolution of birds and flight just got a couple new pages as fossilized footprints in Australia turn out to be the oldest known bird tracks on the continent down under.
"These tracks are evidence that we had sizeable, flying birds living alongside other kinds of dinosaurs on these polar, river floodplains, about 105 million years ago," says lead researcher Anthony Martin, a paleontologist at Emory University in Atlanta.
Researchers analyzing two fossilized tracks from Dinosaur Cove in Victoria, Australia found compelling evidence that the tracks came from birds, and not their reptilian ancestors. Rear-pointing toes and the pattern of the landing track helped giveaway the footprints' owner.
"I immediately knew what it was - a flight landing track - because I've seen many similar tracks made by egrets and herons on the sandy beaches of Georgia," said Martin.
The team of researchers is hoping that the tracks can help shed more light on the evolution of flight, as well as the evolution of birds, who are essentially modern-day dinosaurs.
"In some dinosaur lineages, that rear toe got longer instead of shorter and made a great adaptation for perching up in trees," Martin said. "Tracks and other trace fossils offer clues to how non-avian dinosaurs and birds evolved and started occupying different ecological niches."
The scientists aren't entirely sure if locals or migratory birds made the tracks, however, given the lack of avian fossils in the southern hemisphere, they're still quite happy with the find.
"The picture of early bird evolution in the southern hemisphere is mostly incomplete," Martin said. "But with these tracks, it just got a little better."
You can read the full published study detailing the findings in the journal Palaeonthology.