Modern Australia is known for its array of wildlife: poisonous snakes and spiders, saltwater crocodiles, koalas, kangaroos, and more. The continent was also once home to dinosaurs, including the giant Australotitan and flying pterosaur Haliskia petersensi.
Now, paleontologists have found remains of the world’s oldest known megaraptorid–aka the ‘mega raptor’–and the first evidence of a carcharodontosaurus in Australia. The fossils are described in a study published February 19 in the Journal of Vertebrate Paleontology and reveal what the predator hierarchy unique to Cretaceous Australia might have looked like.
G’day theropods
The megaraptorids and carcharodontosaurus were theropod dinosaurs. Theopods were primarily carnivores and walked on two hind legs. They range in size from the small Coelurosaur up to the giant Tyrannosaurs. Several theropod species also had feathers.
An illustration of a ‘mega raptor. ‘CREDIT: Artwork by Jonathan Metzger. Source–Museums Victoria.
The mega raptors belonged to a family of large-bodied dinosaurs from the Cretaceous Period (about 125 to 66 million years ago) called Megaraptoridae. They were about 20 feet long and have mostly been found in southern continents. Megaraptorids are known for somewhat small–but sharp–teeth, air-filled bones, and powerful forelimbs with enormous claws.
At roughly 45 feet-long, Carcharodontosaurus was among the largest land-dwelling carnivores in our planet’s history. It also lived during the Cretaceous and has primarily been found in North Africa until now.
An illustration of a Carcharodontosaur. CREDIT: Artwork by Jonathan Metzger. Source–Museums Victoria
The dominant predators
Paleontologists uncovered these five new theropod fossils along the coastline in the state of Victoria in southeastern Australia. They were unearthed in the upper Strzelecki Group (about 121.4 to 118 million years old) and the Eumeralla Formation (about 113 to 108 million years old). The fossils suggest that modern-Victoria’s ancient ecosystem was dominated by these powerful theropods.
“The discovery of carcharodontosaurs in Australia is groundbreaking,” Jake Kotevski, a study co-author and Museums Victoria Research Institute and Monash University PhD student, said in a statement. “It’s fascinating to see how Victoria’s predator hierarchy diverged from South America, where carcharodontosaurs reached Tyrannosaurus rex-like sizes up to 13 metres [42.6 feet], towering over megaraptorids. Here, the roles were reversed, highlighting the uniqueness of Australia’s Cretaceous ecosystem.”
Two of the fossils represent the world’s oldest known mega raptors and expand our understanding of the group’s evolutionary history. Australia’s theropod fauna could have played a pivotal 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,” Thomas Rich, a senior curator of vertebrate palaeontology at Museums Victoria Research Institute and study co-author, said in a statement. “The findings also challenge previous assumptions about body-size hierarchies in Gondwanan predator ecosystems highlighting Victoria’s unique Cretaceous fauna.”
Top row: Two Megaraptoridae. Bottom row: Unenlagiinae Carcharodontosauria and Carcharodontosauria Megaraptoridae. CREDIT: Photographer–Nadir Kinani. Source–Museums Victoria.
The volunteer factor
Three of the fossils were uncovered between 2022 and 2023 and were first identified by Museums Victoria volunteer Melissa Lowery. According to the team, this discovery highlights how volunteers and community members working alongside seasoned researchers can help uncover the secrets of Australia’s Cretaceous past.
The team will also keep surveying these key fossil sites, including the spots where the large megaraptorid fossils were uncovered.
