After 128 years of exploration and excavation, Flinders University researchers have uncovered the skull of Australia's “giga-goose”. 

Previously, the only known skull of the giant megafauna bird, Genyornis newtoni, reported in 1913, was heavily damaged with little original bone remaining. 

Recent excavations from the saline, dry beds of Lake Callabonna in inland South Australia have provided new fossils, offering a clearer picture of this extinct species.

Discovered during field trips in 2019, these fossils included a near-complete body, confirming the skull's attribution to Genyornis newtoni, which went extinct around 45,000 years ago. Published in the journal Historical Biology, the description of the skull allows researchers to explore the ecology, functional morphology, and evolutionary relationships of these giant birds.

Genyornis newtoni, weighing approximately 230 kg - around five times the weight of a Southern Cassowary - had a remarkable skull. 

The massive braincase, large jaws, and an unusual casque atop the head are among its notable features. 

The upper beak, in particular, shows surprising morphology, distinguishing this bird from its closest relatives.

“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,” says lead author Phoebe McInerney. 

Aspects of the skull also show complex similarities to early diverging waterfowl lineages, including South American Screamers and the Australian Magpie Goose.

“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,” McInerney says. 

Co-author Dr Trevor Worthy said the team was “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 from any other bird, yet like a goose”.

Examining the skull's morphology also provided insights into the bird's head function, assessing muscles and movement in each joint. 

“The form of a bone, and structures on it, are partly related to the soft tissues that interact with them, such as muscles and ligaments, and their attachment sites or passages. Using modern birds as comparatives, we are able to put flesh back on the fossils and bring them back to life,” said Jacob Blokland, another co-author.

The study also revealed several unusual adaptations for aquatic habitats, protecting the ears and throat from water influx when the head was submerged. 

These adaptations further support Genyornis being a giant prehistoric goose, potentially linking its extinction to the transformation of fresh water bodies in northern South Australia into salt lakes.

More details are accessible here.