Genyornis newtoni, a huge bird that can't fly, lived in Australia until about 45,000 years ago.
New fossil finds have revealed the appearance of these ancient "thunderbirds" and helped us understand why they became extinct.
(Photo: Flickr/James St. John)
A Revelation of the Genyornis Skull
Genyornis Newtoni was two meters tall and weighed up to 230 kilograms. Scientists have been confused for a long time because there aren't many well-preserved skull fossils.
Discoveries, like a complete skull, from the dry salt lakes in northeastern South Australia have given us a better idea of what this ancient bird looked like. Genyornis, which means "jaw bird" in Greek, got its name because it had a tall, strong head with a prominent lower jaw.
Genyornis's upper jaw is long, a little longer than it is wide, and ends in a goose-like point that is spatulate. It has a closed palate and a noticeable ridge running down the middle of the beak.
Above the small nostrils is a bulbous casque, which may be for sexual show. Genyornis's skull had flexible joints that let it open its mouth wide, which suggests it had a strong bite. Strong muscles connected to the back of the braincase supported this.
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Evolutionary Ideas and Way of Life
Since there aren't many older fossils, it's hard to figure out how dromornithids evolved over at least 55 million years. Researchers have learned more about how dromornithids evolved by comparing fossil skulls of dromornithids with skulls of similar landfills and waterfowl. The current publication of this work is in Historical Biology.
Genes from Genyornis are found in both landfowl (like chickens) and waterfowl (like ducks and geese). This means that these traits were present in their most recent shared ancestor.
The jaw muscles and bones of Genyornis are very similar to those of current screamers (Anhimidae), which are South American waterfowl that diverged early. This shows that dromornithids and early ducks have a close evolutionary connection. The new skull backs up earlier ideas about how Genyornis lived, showing that it ate soft, non-fibrous plants like fresh shoots and fruit.
Newly discovered adaptations, like a closed palate and nostrils far back by the eyes, show that Genyornis could eat while submerged in water without losing hearing. These traits show that Genyornis did well in swamps, marshes, and lakes.
Fossils found in these kinds of places support this idea. They show that Genyornis had broad, short toes and claws that looked like hooves for walking on land that was not wet.
The land of Australia probably dried up a lot, which was a big reason why Genyornis went extinct. The bird could no longer depend on wetland areas and new plant growth as big bodies of fresh water turned into dry salt lakes.
Genyornis and the dromornithid family died out because of climate change and dried-up water sources. The exact cause of their extinction is not clear.
A Better Look at the Giant "Thunder Birds"
New fossil finds have given us a better idea of what Genyornis looked like and how they lived, but there are still many questions.
Scientists will examine the bones in their inner ears to learn more about how these vast birds moved. This study could provide new information about how they moved and changed over time to fit their surroundings.
These findings have clarified the quick evolution of these fascinating "thunderbirds" and prehistoric Australia. As paleontologists continue to unearth and examine these ancient bones, more about the lives and demise of these incredible creatures is probably to come.
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