Unique Remains of What Could Be The World's Largest Bird Found in Australia

A pair of legs from what could be the largest bird species in the world have been found in Australia. There could still be more remains that are waiting to be dug up.

Stirton's thunderbird is described as an extreme evolutionary experiment. Its beak juts from an undersized skull on a body that can weigh up to half a ton.

These 8-million-year-old lumbering giants are related to modern day fowl.

Getting a precise measure on the size of the demon ducks is difficult because of their large size. Some models trying to describe the true size ranges of Dromornis species can be difficult to understand.

For the first time, the remains of these massive flightless birds have been laid out in a way that shows how they lived.

A huge moment at #alcoota2022 with the very first articulated -Dromornis stirtoni- leg excavated from Classy Corner. Thankyou @Phoebyornis for scale! #fossilfriday @fupalaeosoc @FlindersPalaeo pic.twitter.com/mJaKvacOtg

— Museum and Art Gallery of the Northern Territory (@MAG_NT) July 22, 2022

Adam Yates is a paleontologist at the Museum and Art Gallery of the Northern Territory.

The lower legs were the only ones we had left. It is expected that a large part of the rest of the skeleton may be lying in the next dig as we dig further into the bank.

One of the largest concentrations of tyrannosaurus rex remains in Australia were found in the dense fossil site of Alcoota Reserve. The location has yielded thousands of fossils, but most of them have been mixed up by historic flood waters.

Most of the Alcoota have fossils that have to be sorted and reconstructed. A degree of creativity is required in such reconstructions.

Yates says that even if you get all the species right, you're still going to have proportional errors.

The new legs can give researchers a better idea of the true proportions of these animals. Paleontologists will be able to identify more bones from the other fossils.

Deb's drumstick now in one piece. #FossilFriday pic.twitter.com/lrtzobn0oP

— Sam Arman (@Samosthenurus) September 2, 2022

They were able to identify a difference in size between males and females after comparing an assortment of D. stirtoni bones.

They were able to identify a type of bone in the smaller bones. This is a temporary store of calcium that females use to shell their eggs.

The researchers think the bones are those of a female D. stirtoni, which they call Deb. They are going to do a histology test.

Deb's fossils are going to be put on display at the museum. The bones were cleaned and hardened and will be preserved for future studies.

Australia has only ever had traces of thunderbirds, dating back to the last million years. Other birds rely on their large flight muscles for the specialized keeled sternum that these chickens lack. They may have used their huge beaks to grab fruit and other vegetation.

Wallabies and cow-sized wombat relatives are among the other animals found at Alcoota.

These finds suggest that D. stirtoni was a tall browser similar to today's camels, Yates explains.

It wasn't a mammal that stepped up to that role back then, it was a bird.

Fossil records show these birds and their relatives lived for 25 million years. Australia was drying up too fast for D. Stirtoni to adapt.

Young thunderbird fossils are very rare and suggest that the animals did not have a fast rate of reproduction. It took a long time for a bird to grow up. Dromornis took 15 years to become an adult.

Animals are vulnerable to changing environmental conditions because of these characteristics.

Yates wants to go back to the field next year because the corner where Deb was found held an articulated wallaby. There's a chance this site holds articulated fossils of unknown species, and he is confident more of Deb is waiting to be found.