Scientists unearth the world’s oldest known megaraptorid fossil

Groundbreaking research has unveiled fossils of the world’s oldest megaraptorid and the first carcharodontosaur remains found in Australia.

These discoveries, published in the Journal of Vertebrate Paleontology, redefine the evolutionary history of theropod dinosaurs and reveal a unique predator hierarchy in Cretaceous Australia.

For decades, Australia’s fossil record has offered limited insight into its theropod diversity. While South America and Africa yielded abundant remains of carcharodontosaurs, megaraptorids, and abelisauroids, Australia’s theropods remained largely unknown.

Previous studies suggested the continent’s prehistoric ecosystem was dominated by small- to medium-sized megaraptorids, with minor contributions from abelisauroids and bird-like unenlagiines. The absence of large carcharodontosaurs was a long-standing mystery—until now.

A team led by Museums Victoria Research Institute and Monash University PhD student Jake Kotevski analyzed five newly discovered theropod fossils from Victoria. These fossils, unearthed along the coastline in the upper Strzelecki Group (about 121–118 million years old) and the Eumeralla Formation (about 113–108 million years old), include three tibiae and two articulated tail vertebrae.

Two of the tibiae provide the first clear evidence of carcharodontosaurs in Australia. These predators, once thought to be absent from the region, coexisted with megaraptorids in a strikingly different ecosystem than their South American relatives.

In contrast to South America, where carcharodontosaurs dominated as top predators, in Australia, they were smaller (2–4 meters long) and seemingly occupied a secondary role to megaraptorids, which grew to an imposing 6–7 meters.

"The discovery of carcharodontosaurs in Australia is groundbreaking," says Kotevski. "In South America, they reached Tyrannosaurus rex-like sizes, towering over megaraptorids. Here, the roles were reversed, highlighting the uniqueness of Australia’s Cretaceous ecosystem."

The discovery also includes the world’s oldest known megaraptorid, pushing back the timeline of their evolution. Previously, megaraptorids were believed to have emerged later in the Cretaceous, but this finding suggests their evolutionary origins may be even older than expected.

These findings challenge previous assumptions about predator dominance in Gondwanan ecosystems. According to Dr. Thomas Rich, senior curator of vertebrate paleontology at Museums Victoria Research Institute, the fossils provide compelling evidence of a faunal connection between Australia and South America through Antarctica during the Early Cretaceous.

"The findings expand Australia’s theropod fossil record and offer insight into how dinosaurs moved between continents," Rich explains. "This discovery also challenges previous ideas about body-size hierarchies in predator ecosystems, showing Victoria’s unique Cretaceous fauna operated under different rules."

The presence of unenlagiines, a group of small, agile, raptor-like dinosaurs, further supports this connection. These creatures, which include Buitreraptor and Austroraptor from South America, suggest that dinosaur lineages crossed between continents more frequently than once thought.

The research underscores the importance of museum collections in scientific breakthroughs. Tim Ziegler, vertebrate paleontology collection manager at Museums Victoria Research Institute, emphasizes that fossils preserved for decades are now revealing new insights.

"Specimens stored in the State Collection, previously unidentifiable, are helping us piece together the evolution of dinosaur ecosystems," Ziegler says.

Three of the fossils were initially identified by Museums Victoria volunteer Melissa Lowery, demonstrating the valuable role of community members in paleontology. "This discovery shows how volunteers can make real contributions to science," Kotevski adds.

The team continues surveying key fossil sites, focusing on areas where the large megaraptorid was found. This work is part of the long-running Dinosaur Dreaming project, which has uncovered more than 10,000 fossil bones and teeth since its inception.

The project has identified at least seven different dinosaurs, along with early mammals, birds, pterosaurs, plesiosaurs, turtles, and fish.

The discovery of these fossils opens new questions about Australia’s prehistoric past. How did these predator species evolve alongside one another? What environmental factors led to the reversal of predator dominance compared to South America? Further excavations and research will help answer these mysteries.

This study marks a turning point in understanding Australia’s Cretaceous dinosaurs. It highlights not only the continent’s distinct predator ecosystem but also its role in broader dinosaur evolution. With continued exploration and fossil discoveries, the story of Australia’s ancient past is still being written.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

Like these kind of feel good stories? Get The Brighter Side of News' newsletter.