The continent of Australia contains a diverse range of wildlife, from poisonous snakes and spiders to koalas, kangaroos, and more. It was also once home to dinosaurs, including the Australotitan and the flying pterosaur Haliskia petersensi.
Now, paleontologists have come across the oldest known remains of a megaraptorid, also known as the mega raptor, as well as the first evidence of a carcharodontosaurus in the region. The fossils reveal what predators were most dominant in Cretaceous Australia.
The megaraptorids and carcharodontosaurus were theropod dinosaurs, which walked on two hind legs and were mainly carnivores. Several theropod species had feathers.
The mega raptors belonged to Megaraptoridae, a family of large dinosaurs that lived during the Cretaceous Period about 125 to 66 million years ago.
They were around 20 feet long and have mostly been discovered in southern continents. They are known for their air-filled bones, small, sharp teeth, and powerful, clawed forelimbs.
Carcharodontosaurus was among the largest land carnivores in the history of our planet at, roughly 45 feet long. It also lived in the Cretaceous Period. Until now, it has primarily been found in North Africa.
Five new theropod fossils were uncovered along the coastline in the state of Victoria, located in southeastern Australia. They were dug up from the upper Strzelecki Group and the Eumeralla Formation.
“The discovery of carcharodontosaurs in Australia is groundbreaking,” said Jake Kotevski, a co-author of the study and a PhD student at Monash University and the Museums Victoria Research Institute.
“It’s fascinating to see how Victoria’s predator hierarchy diverged from South America, where carcharodontosaurs reached Tyrannosaurus rex-like sizes up to [42.6 feet], towering over megaraptorids. Here, the roles were reversed, highlighting the uniqueness of Australia’s Cretaceous ecosystem.”
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The fresh findings show that the two apex predators would have lived at the same time and fought over the same prey.
Two of the fossils represent the oldest known mega raptors in the world, broadening scientific knowledge of the group’s evolutionary history.
Additionally, Australia’s theropod fauna could have played a major role in the ecosystems of the ancient supercontinent Gondwana.
“The findings not only expand Australia’s theropod fossil record but offer compelling evidence of faunal interchange between Australia and South America through Antarctica during the Early Cretaceous,” said Thomas Rich, a co-author of the study and a senior curator of vertebrate paleontology at Museums Victoria Research Institute.
“The findings also challenge previous assumptions about body-size hierarchies in Gondwanan predator ecosystems highlighting Victoria’s unique Cretaceous fauna.”
In 2022 and 2023, three of the fossils were unearthed. The research team will keep examining these fossil sites for more clues as to what dinosaurs looked like many millions of years ago.
The study was published in the Journal of Vertebrate Paleontology.
