New Australian dinosaurs and the oldest megaraptorid fossils in the world

(Press-News.org) Groundbreaking research published today in the Journal of Vertebrate Paleontology has unveiled a landmark discovery – fossils of the world’s oldest known megaraptorid and the first evidence of carcharodontosaurs in Australia. These finds rewrite the evolutionary history of theropod dinosaurs, uncovering a predator hierarchy unique to Cretaceous Australia.

The research, led by Museums Victoria Research Institute and Monash University PhD student Jake Kotevski, describes five theropod fossils discovered along Victoria’s coastline. The fossils were unearthed in the upper Strzelecki Group (Bunurong/Boonwurrung Country, Bass Coast, ~121.4-118 million years ago) and the Eumeralla Formation (Eastern Marr Country, Otway Coast, ~113-108 million years ago).

These fossils offer new insights into Victoria’s ancient ecosystem, which was dominated by large powerful megaraptorids (6–7 metres long) alongside smaller carcharodontosaurs (2–4 metres long) and agile, metre-long unenlagiines, or ‘southern raptors’.

‘The discovery of carcharodontosaurs in Australia is groundbreaking,’ says Kotevski. ‘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, towering over megaraptorids. Here, the roles were reversed, highlighting the uniqueness of Australia’s Cretaceous ecosystem.’

Two of the fossils represent the oldest known megaraptorids globally, expanding our understanding of the group’s evolutionary history and suggesting Australia’s theropod fauna played a pivotal role in Gondwanan ecosystems.

Dr Thomas Rich, senior curator of vertebrate palaeontology at Museums Victoria Research Institute, explains, ‘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. The findings also challenge previous assumptions about body-size hierarchies in Gondwanan predator ecosystems highlighting Victoria’s unique Cretaceous fauna.’

The research demonstrates the vital role of museum collections in building on scientific knowledge and fostering significant scientific breakthroughs. ‘Museum collections are crucial to advancing our understanding of prehistoric life,’ says Tim Ziegler, vertebrate palaeontology collection manager at Museums Victoria Research Institute. ‘Specimens preserved in the State Collection for decades – unidentifiable until now – are providing new insights into the evolution of dinosaur ecosystems.’

Additionally, the research illustrates the multigenerational efforts of Museums Victoria Research Institute palaeontologists. From senior curator Dr Thomas Rich, who has been with the museum since 1974, to collection manager Tim Ziegler and onto the next generation in PhD student Jake Kotevski, this study is one example of the collective efforts of our scientists in creating and sharing trusted knowledge.

Three of the fossils, uncovered between 2022 and 2023, were first identified by Museums Victoria volunteer Melissa Lowery. This discovery highlights the essential contributions of community members working alongside seasoned researchers to further our understanding of Australia's Cretaceous past.

Kotevski and the team continue to survey key fossil sites, including where the fossils of the large megaraptorid were discovered, prompting new avenues of investigation for the Dinosaur Dreaming project, which has led to many significant discoveries including more than 10,000 fossil bones and teeth since the project began – including at least seven different dinosaurs, three groups of mammals, birds, pterosaurs, plesiosaurs, turtles and fishes.

To learn more about Victoria’s ancient ecosystems and fauna, visit Melbourne Museum’s 600 Million Years: Victoria Evolves exhibition and Gandel Gondwana Garden.

This research is a collaboration between Museums Victoria Research Institute and Monash University.

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