Ancient relative of geese is the earliest known modern bird

A 69-million-year-old skull found in Antarctica has been identified as a relative of geese and ducks, making it the oldest known modern bird.

It belongs to a species that was first identified two decades ago named Vegavis iaai, which lived in the late Cretaceous Period alongside the last dinosaurs. But because only fragments of skulls had been found previously, scientists had been unable to agree what kind of bird it was or whether it was instead a bird-like, non-avian dinosaur.

The fossil skull was discovered in 2011 on Vega Island, off the Antarctic Peninsula. However, it was encased in rock so hard that excavators had to spend hundreds of hours chipping away at the surrounding stone before it could be scanned to reveal its internal details.

Patrick O’Connor at Ohio University, who worked on the analysis, says two features of the almost complete skull only ever occur in modern birds. First, the upper beak is primarily comprised of a bone called the premaxilla, while a second bone, the maxilla, is greatly reduced in size and contributes to only a small portion of the bony palate.

Second, in modern birds, the forebrain is massive relative to the rest of the brain; in pre-modern birds and near-bird dinosaurs like Velociraptor, these areas are proportionally much smaller.

While Vegavis has features that clearly mark it as being in the same group of waterfowl as ducks and geese, it would have looked very different, says O’Connor. The bird’s beak shape, jaw musculature and hind limbs suggest it was highly specialised for diving in pursuit of fish.

“It would probably be easily mistaken for modern grebes or loons, which are only distantly related to ducks and to each other,” he says.

Jacqueline Nguyen at the Australian Museum in Sydney says this ancient species has been subject to a lot of debate among avian evolutionary scientists, but the new research helps settle the argument.

“Together, [the evidence] suggests that Vegavis looked and foraged quite differently from its duck and geese relatives, and that this may have been an ‘evolutionary experiment’ in the early history of this group of birds,” she says.

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