Newly Unearthed Skull Reveals Extinct Giant Bird in Australia

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For over a hundred years, scientists have been on the lookout for skull fossils of the thunder bird species Genyornis newtoni. These giants, also called mihirungs, roamed the forests and grasslands of Australia around 50,000 years ago. Standing taller than humans and weighing hundreds of kilograms, they were known for their muscular legs.

Around 45,000 years ago, the last of the mihirungs became extinct. A skull, discovered in 1913, was incomplete and badly damaged, leaving scientists with many questions about the giant bird's appearance, behavior, and lineage.

However, a recent discovery of a complete G. newtoni skull has finally provided answers to this long-standing mystery. Scientists now have the opportunity for their first face-to-face encounter with the massive mihirung.

And it has the face of a very strange goose.

Pictured here is the skull of G. newtoni, which is helping resolve a long-standing mystery about the giant bird's face.

Pictured here is the skull of G. newtoni, which is helping resolve a long-standing mystery about the giant bird's face.

Courtesy Flinders University

G. newtoni, a member of the family Dromornithidae, was a large bird standing about 7 feet tall and weighing up to 529 pounds. This group of flightless birds is known from fossils found in Australia.

A significant discovery was made between 2013 and 2019 by a team of paleontologists in southern Australia’s Lake Callabonna. They found multiple skull fragments, a skeleton, and an articulated skull, providing valuable insights into G. newtoni. This discovery also revealed connections between G. newtoni and modern waterfowl like ducks, swans, and geese, as reported in the journal Historical Biology.

Though Genyornis has been known to scientists for more than a hundred years, the new fossils and reconstruction provide important missing information, according to Larry Witmer, a professor at Ohio University who specializes in anatomy and paleontology and was not part of the research team.

Exhibition at the National Museum of Natural History in Paris, Trix, one of the best preserved fossils of Tyrannosaurus rex (T-rex) on 8 June 2018 in Paris, France. (Photo by Olivier Donnars/NurPhoto via Getty Images)

Trix, one of the best preserved fossils of Tyrannosaurus rex (T-rex), was displayed at the National Museum of Natural History in Paris on 8 June 2018. The exhibition showcased this remarkable fossil to the public in Paris, France. (Photo by Olivier Donnars/NurPhoto via Getty Images)

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"The skull is highly valued because it holds a lot of important information," explained Witmer. "It houses the brain, sense organs, feeding apparatus, and often serves as the location for display organs like horns, crests, wattles, and combs. Additionally, skulls provide valuable insights into the ancestry of the species."

In the recent study, Witmer noted that "the researchers thoroughly examined the new fossils." They not only studied the bone structures of the skull but also analyzed the placement of jaw muscles, ligaments, and other soft tissues to gain a better understanding of the bird's biology.

“This latest discovery of new Genyornis skulls has really helped fill in the blanks,” Witmer said.

‘Very goose-like’

A digital reconstruction puts the newfound skull of G. newtoni in the spotlight. Lead study author Phoebe McInerney, a vertebrate paleontologist at Flinders University in South Australia, used other skull fossils and data from modern birds to reveal new insights about its appearance.

After 128 years since its discovery, McInerney stated that they now have a clearer picture of what Genyornis looked like. The bird had a distinctive beak that resembled that of a goose.

G. newtoni’s skull is shorter than most other birds, but it has massive jaws supported by strong muscles. According to McInerney, they would have had a very wide gape.

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120 million years ago, the 'Strange bird' specimen may have appeared similar to other birds, but there was something unique about it when it opened its mouth.

The skull of G. newtoni provided clues about its diet. It had a flat gripping zone in its beak that was perfect for tearing soft fruits, tender shoots, and leaves. Additionally, the flattened palate on the underside of the upper bill may have been utilized for crushing fruits into a pulp.

“We found evidence suggesting that they probably ate soft food, and the new beak confirmed that,” McInerney mentioned. “Additionally, the skull displayed signs of adjustments for feeding in water, possibly on freshwater plants.”

Witmer expressed surprise at the idea of underwater feeding for G. newtoni, considering its large size.

"It's not too surprising that dromornithids like Genyornis are related to ducks and geese. Genyornis stood six or seven feet tall and weighed up to 500 pounds," explained Witmer. Further fossil findings could provide insight into whether these adaptations were traits passed down from aquatic ancestors, or if these large birds were actually venturing into shallow waters to find vegetation.

"It's like a strange mix," said Witmer.

The study authors reported that the reconstruction of dromornithids helped scientists resolve their conflicted lineage. They were placed within the waterfowl order Anseriformes. Based on bone structures and associated muscles, dromornithids were likely close relatives to ancestors of modern South American screamers, which are ducklike birds inhabiting wetlands in southern South America.

Scientists propose placing Genyornis newtoni within the waterfowl clade. The illustration also highlights how G. newtoni stacks up sizewise to its closest relative, Anhima cornuta (nearest to G. newtoni) and the cassowary (not related).

Scientists suggest that Genyornis newtoni should be classified within the waterfowl group. A comparison illustration shows the size difference between G. newtoni, its closest relative Anhima cornuta, and the unrelated cassowary.

Study coauthor and avian paleontologist Jacob Blokland from Flinders University pointed out that while G. newtoni had a beak resembling that of a goose, its face did not perfectly match modern geese. He shared reconstructions of the skull and the appearance of G. newtoni in life, noting that it had some similarities to parrots and landfowl despite not being closely related to them. Blokland found it fascinating how G. newtoni appeared goose-like yet distinct from any existing goose species we know today.

Blokland started the new reconstruction by focusing on the bony external ear region, as there were many specimens that preserved this part. He then created a scaffold that was consistent across various skull fossils. Some parts of the reconstruction were informed by skulls of other dromornithids or modern waterfowl, and studies of modern birds helped in understanding how muscles and ligaments could have moved the bones.

A previously unknown detail that the study authors reported was the presence of a wide triangular bony shield called a casque on the upper bill. This feature could have been used for sexual displays.

Two of the study's coauthors, Phoebe McInerney and Jacob Blokland, pose with a skull of Genyornis newtoni.

Two of the study's coauthors, Phoebe McInerney and Jacob Blokland, pose with a skull of Genyornis newtoni.

Big, flightless emus and cassowaries can be found in Australia, but they are not closely related to thunder birds. According to McInerney, these creatures are much smaller in comparison to the long-lost mihirungs, which still capture people's imagination. There is still a lot to learn about the anatomy of these extinct giants. For example, it is not yet known how gigantism and flightlessness may have impacted the inner ear structures related to head stabilization and movement.

The new perspective on G. newtoni is the most accurate to date, but more fossils are needed to fully understand this unusual giant goose, the last of the mighty thunder birds, and its lost habitat, according to Blockland.

Blockland mentioned, "This giant and one-of-a-kind bird definitely had an impact on the environment and the other animals it came into contact with, regardless of their size. Through research, we can uncover more about what we have yet to learn."

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.

Editor's P/S:

The recent discovery of a complete skull of Genyornis newtoni, a giant thunder bird that roamed Australia 50,000 years ago, has provided scientists with unprecedented insights into its appearance and behavior. Despite its massive size, the bird's skull resembles that of a goose, with a wide gape and a beak adapted for tearing soft fruits and leaves. The discovery has also revealed that dromornithids, the group to which G. newtoni belonged, were closely related to ancestors of modern South American screamers, rather than emus or cassowaries.

This discovery not only sheds light on the evolution of thunder birds but also highlights the importance of fossil discoveries in reconstructing the history of life on Earth. The complete skull of G. newtoni has finally allowed scientists to answer long-standing questions about its appearance and behavior, providing a more accurate picture of this extinct giant. Further fossil findings and research can potentially reveal more about the anatomy of these creatures, their ecological impact, and the reasons for their extinction.