May 29, 2013
Fossil Find Gives Ancient Bird Back Its Heritage
Lee Rannals for redOrbit.com — Your Universe Online
A new discovery made by paleontologists digging in China has put Archaeopteryx back on the map as one of the earliest birds.
Archaeopteryx was first discovered in 1861 and, at the time, was professed to be the world's earliest bird. However, in 2011 researchers carried out a phylogenetic analysis and determined that the Archaeopteryx was actually just another feathered dinosaur. If this team was right, it would mean flight evolved at least four times in vertebrates. The team even cautioned back then, though, that the next feathered fossil unearthed in China could restore the status of the ancient creature. They were right.
Scientists writing in the latest edition of Nature are putting Archaeopteryx back on the map as being one of the world's first true birds with the discovery of Aurornis xui. This fossil animal is dated about 160 million years old and actually predates Archaeopteryx.
Aurornis, which means "dawn bird," was about the size of a chicken and emerged about 10 million years earlier than Archaeopteryx. It had claws and a long tail, with front and hind legs similar to Archaeopteryx. The Aurornis fossil was preserved in sedimentary rock and had traces of feathers along the animal's tail, neck and chest. The scientists said the absence of larger feathers suggests the bird was actually not able to fly.
"It's an important fossil," Gareth Dyke, a senior paleontologist involved in the study at Southampton University told The Guardian. "Aurornis pushes Archaeopteryx off its perch as the oldest member of the bird lineage."
The researchers' study doesn't just re-classify Archaeopteryx as a bird; it also re-shuffles the Troodontidae, which is a family of bird-like dinosaurs.
"What we're arguing over here is actually very small, esoteric features of the anatomy," Dr. Paul Barrett from the Natural History Museum, London told the BBC. "We're looking at a nexus of animals around bird origins - birds themselves and a bunch of dinosaurs that are almost, but not quite, birds."
He said just one or two changes across a huge body of data can make the difference between an animal being on one side of this bird-dinosaur divide or the other.
"The beginnings of the bird line is all about fine-tuning parts of their anatomy - of their wings, of their hips, of their chest muscles and shoulder girdles, and so on - to make them flight-ready," he told BBC News.