A nearly complete fossilized skull of an ancient extinct bird may end the debate among paleontologists about the first feathered birds.
An extinct species, Vegavis (Vegavis iaai) inhabited what is now Antarctica about 69 million years ago, at the end of the Cretaceous period. The newly described fossil confidently places the earliest known
modern birds among the ancient relatives of ducks and geese (waterfowl).
"Few birds can cause as much controversy among paleontologists as vegavis," said Dr. Christopher Torres of Ohio University and the University of the Pacific in the United States, lead author of a study in the journal Nature describing the find. "This new fossil will help resolve many of these debates. Chief among them: what place does vegavis occupy in the tree of bird life?""
Vegavis was discovered 20 years ago through the discovery of a partial skeleton, and was originally thought to be an early representative of modern birds, also known as a group of warm-blooded egg-laying vertebrates (Aves), and in particular geese (Anseriformes). However, this place on the tree of bird life has remained controversial ever since.
Fossils of modern birds are exceptionally rare until 66 million years ago, when an asteroid impact near Mexico's Yucatan Peninsula led to the extinction of all known non-bird dinosaurs, and more recent studies have cast doubt on the evolutionary position of vegavis.
"In the few places where significant fossils of Late Cretaceous birds survive, such as Madagascar and Argentina, you can find an entire aviary of bizarre, now extinct species with teeth and long bony tails that only remotely resemble modern birds," said Dr. Patrick O'Connor of Ohio University and the Denver Museum of Nature and Science, co-author of the study. "It appears that something very different was happening in the distant Southern Hemisphere, specifically Antarctica."
The new fossil, found during an expedition to the Antarctic Peninsula in 2011, has something that all previous fossils of the bird in question did not have - a nearly complete skull.
Photo: cosmosmagazine.com
It retained skull features characteristic of modern birds, particularly waterfowl, such as the shape of the brain and a long, narrow beak devoid of teeth.
Microcomputer tomography of the skull shows that vegavis had powerful jaw muscles that were used to overcome water resistance when diving to catch fish.
These features are consistent with other features found in other parts of the Vegavis skeleton, which indicate that the species used its paws to move underwater in pursuit of fish and other prey.
Unlike modern waterfowl, this feeding strategy is closer to the likes of birds in the Pogan family and loons. "This fossil emphasizes that Antarctica can tell us a lot more about the earliest evolutionary stages of modern birds," says O'Connor.