A skull solves ancient waterfowl puzzle

A new fossil of a bird that lived around 68 million years ago in Antarctica confirms its identity as an early waterfowl. The near-complete skull, described in Nature this week, belongs to a bird called Vegavis that cohabited the planet when giant dinosaurs like Tyrannosaurus and Triceratops ruled the land.

The discovery represents an early member of waterfowl (ducks and geese). It is named Vegavis after Vega Island, the island near the Antarctic Peninsula where the fossil was discovered, and the Latin term for bird (avis).

Previous specimens of Vegavis either consisted of skeletons without a skull or partial skull elements, such as a portion of the mandible, leaving much uncertainty regarding the bird’s classification within the avian family. The limited evidence hinted towards it being a relative of modern waterfowl. Still, the lack of a complete skull meant that there was some uncertainty about the bird’s identity and its place on the avian evolutionary tree.

Vegavis was first reported 20 years ago. At that time, it was proposed as an early member of modern birds and evolutionarily nested within the waterfowl community. However, modern birds were exceptionally rare before the Cretaceous extinction. Subsequent studies cast doubt on the evolutionary position of Vegavis.

All theories have been put to rest by the new fossil that has something that each of the previous specimens lacked: a nearly complete skull. The new skull helps lay that scepticism to rest, preserving several traits like the shape of the brain and beak bones that are consistent with modern birds, specifically waterfowl. But unlike most modern-day waterfowl species, the skull preserves traces of powerful jaw muscles useful for overcoming water resistance while diving to snap up fish.

The skull features are also 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 strategy more like other modern birds like grebes and loons.

A team led by scientists at Ohio University generated a near-complete three-dimensional reconstruction of the new skull. The analyses reveal a typical avian brain shape and strongly support the placement of Vegavis within the waterfowl family and as a close relative of ducks and geese.

The analysis also shows that Vegavis has a slender, pointed beak powered by enhanced jaw muscles, a feature that is less like other known waterfowls but more like diving birds.

“The fossil underscores that Antarctica has much to tell us about the earliest stages of modern bird evolution,” says Patrick O’Connor, one of the co-authors of the study and a professor at Ohio University.