Geese have a reputation for being aggressive, unpleasant birds, so imagine one that’s more than 2 m (6.6 ft) tall and weighs about 230 kg (507 lb). That’s Genyornis newtoni, an Ice Age “thunder bird” from Australia, for which scientists have now found the first complete skull.

Indigenous Australians lived alongside some incredible megafauna for tens of thousands of years. That includes a clade of gigantic flightless birds scientifically known as Dromornithidae, or mihirungs in the language of the Djab Wurrung people. Informally, they’re sometimes called “thunder birds” or “demon ducks,” thanks to their huge size and surprising relation to ducks and geese.

The last known species, Genyornis newtoni, went extinct about 45,000 years ago, meaning they had some crossover with the first humans to call the land home. But one important piece of the puzzle was missing from fossil records: the only known skull, described in 1913, was too damaged to deduce much about what the head looked like, especially the upper jaw.

Now, scientists have discovered the first intact skull of the species, revealing more about what the bird looked like and how it behaved. It was found to have a huge braincase, large jaws, and a bony crest on the top of its head called a casque. Such features are similar to those of other species in the early waterfowl lineages.

“The exact relationships of Genyornis within this group have been complicated to unravel, however, with this new skull we have started to piece together the puzzle which shows, simply put, this species to be a giant goose,” said Phoebe McInerney, lead author of the study. “Genyornis newtoni had a tall and mobile upper jaw like that of a parrot but shaped like a goose, a wide gape, strong bite force, and the ability to crush soft plants and fruit on the roof of their mouth.”

Photo: Flinders University. Illustration: Jacob Blokland

The team also found clues which suggest the bird had unusual adaptations that would have helped it live a semi-aquatic lifestyle. For instance, bones of the inner ear have a certain shape that would prevent water flooding into the ears and throat when the head is submerged.

The skull was discovered in the dry, salty beds of Lake Callabonna, South Australia, where the team was able to confirm that it belonged to Genyornis because it was found near almost-complete skeletons of the species. The find allowed scientists to produce the most accurate recreation of the bird’s head so far, as seen in the image at the top of this article.

“We were particularly excited to discover the first fossil upper bill of Genyornis, for the first time we could put a face on this bird, one very different to any other bird, yet like a goose,” said Dr. Trevor Worthy, co-author of the study.

The research was published in the journal Historical Biology.

Source: Flinders University via Scimex