Scientists discover skull of oldest known modern bird

By Stephen Beech

The fossilized 69-million-year-old skull of the oldest known modern bird has been discovered.

The early relatives of ducks and geese lived in Antarctica at around the same time Tyrannosaurus rex dominated North America, say scientists.

An asteroid impact near the Yucatán Peninsula of Mexico around 66 million years ago, at the end of the Cretaceous Period, triggered the extinction of all known non-bird dinosaurs.

But the early ancestors of today’s waterfowl survived that mass extinction event.

Scientists believe Antarctica may have served as a refuge, protected by its distance from the turmoil taking place elsewhere on the planet.

Fossil evidence suggests a temperate climate with lush vegetation, possibly serving as an "incubator" for the earliest members of the group that now includes ducks and geese.

The new research, published in the journal Nature, describes an important new fossil of the oldest known modern bird.

The fossil, a nearly complete, 69-million-year-old skull, belongs to an extinct bird named Vegavis iaai and was collected during a 2011 expedition by the Antarctic Peninsula Palaeontology Project.

The new skull exhibits a long, pointed beak and a brain shape unique among all known birds previously discovered from the Mesozoic Era when non-avian dinosaurs and a bizarre collection of early birds dominated Earth.

Researchers say the features place Vegavis in the group that includes all modern birds, representing the earliest evidence of a now widespread and successful evolutionary radiation across the planet.

Study lead author Dr. Christopher Torres, a National Science Foundation (NSF) Postdoctoral Fellow at Ohio University, said: “Few birds are as likely to start as many arguments among paleontologists as Vegavis.”

Dr. Torres, now a Professor at the University of the Pacific, added: “This new fossil is going to help resolve a lot of those arguments.

"Chief among them: where is Vegavis perched in the bird tree of life?”

Vegavis was first reported 20 years ago by study co-author Dr. Julia Clarke, of The University of Texas at Austin, and several colleagues.

At that time, it was proposed as an early member of modern - also known as crown - birds that were evolutionarily nested within waterfowl.

But modern birds were exceptionally rare before the end of the Cretaceous extinction, and more recent studies have cast doubt on the evolutionary position of Vegavis.

The specimen described in the study has something that all previous fossils of this bird have lacked: a nearly complete skull.

Several traits - including the shape of the brain and beak bones - are consistent with modern birds, specifically waterfowl.

Unlike most of today's waterfowl, the research team says the skull preserves traces of powerful jaw muscles useful for overcoming water resistance while diving to snap up fish.

The skull features are consistent with clues from elsewhere in the skeleton, suggesting that Vegavis used its feet for underwater propulsion during the pursuit of fish and other prey – a feeding method unlike that of modern waterfowl and more like that of some other birds such as grebes and loons.

Co-author Professor Patrick O’Connor, also of Ohio University, said: “This fossil underscores that Antarctica has much to tell us about the earliest stages of modern bird evolution."

He says birds known from elsewhere on the planet at around the same time are "barely recognizable" by modern bird standards.

Most of the handful of sites that even preserve delicate bird fossils yield specimens that are so incomplete as to only give hints to their identity, as was the situation with Vegavis until now.

O'Connor added: “And those few places with any substantial fossil record of Late Cretaceous birds, like Madagascar and Argentina, reveal an aviary of bizarre, now-extinct species with teeth and long bony tails, only distantly related to modern birds.

"Something very different seems to have been happening in the far reaches of the Southern Hemisphere, specifically in Antarctica."

Study co-author Dr. Matthew Lamanna, of Carnegie Museum of Natural History, said: “Antarctica is in many ways the final frontier for humanity’s understanding of life during the Age of Dinosaurs.”

O’Connor added: “Large-scale projects like this one, involving students and postdoctoral researchers, prepare the scientists of tomorrow to collaborate, advance science, and tackle the biggest questions facing our planet,”