|The opalised section of claw, displaying its blue colouration|
Unusually, a few of the fossils were opalised, giving them a pale blue colour. Analysis of the specimens involved simple ratios to extrapolate the creature's original size. Incredibly it came in at seven metres, making it the largest species of carnivorous dinosaur yet found on the continent.
The specimens have yet to be assigned a new species name, but their morphology demonstrates that the species belongs to the megaraptorid group of theropod dinosaurs. The megaraptorids lived on the southern continent of Gondwana. Yet they were particularly prevalent in South America, so it was long thought that they originated there and then migrated across Gondwana, resulting in the handful of Australian known specimens. This new species suggests the opposite: that the megaraptorids originated in Australia.
|An artist's impression of the as-of-yet unnamed megaraptorid dinosaur|
Phylogenetic analysis suggested an Asian origin of the wider megaraptora group in the latest Jurassic around 150-135 million years ago, an early Cretaceous divergence of the Gondwanan lineage leading to the megaraptorid group at around 130 to 121 million years ago, and ultimately an Australian root for megaraptorid radiation. The products of this radiation would have subsequently spread across Gondwana from their Australian homeland to future South America.
'This specimen provides new evidence that Australia played an active role in the evolution and radiation of at least one group of apex theropods. Significantly, the Australian origin of megaraptorid theropods is echoed by eusuchian crocodylomorphs wherein Isisfordia duncani from the Lower Cretaceous of Queensland suggests the origin of this clade also has an Australian root.'