An artist’s illustration of the new theropod dinosaur, Invictibellatrix amberina Meet _Invictibellatrix amberina,_ the unconquered female warrior – a new species of predatory dinosaur related to _Tyrannosaurus rex_ that hails from the Isle of Wight in southern England. The fossil used to identify it – a partial braincase – has been lying in the archives of the Natural History Museum in London since it was acquired from a Reverend Reginald Hooley in 1924. Morrison and his colleagues used CT scans to create a 3D scan of the fossil and compared it with features of other dinosaurs.
The closest match was the Argentinian megaraptoran _Murusraptor_ from about 80 million years ago. So, the researchers suggest that the skull, originally found in 120-million-year-old rocks from the Lower Cretaceous Wessex Formation on the south-west coast of the Isle of Wight, is from a new species belonging to the Megaraptora group of carnivorous dinosaurs. If so, it is the first time a megaraptoran has been discovered in Europe.
The fossil braincase of Invictibellatrix amberina _._ The oval hole is where the brain would have been A similar-looking dinosaur is known from a few million years earlier in the Wessex Formation: the 5-metre-long _Eotyrannus_. However, the parts we have hint that it belonged to the sister group of tyrannosaurs and none of the fossilised remains of the two individuals directly overlap, so it is hard to compare them. The genus name Morrison and his colleagues have given to the newly described fossil, _Invictibellatrix_, means female unconquered warrior.
They estimate that it was an agile, two-legged carnivore that was about 3 to 4 metres long, some 1.5 metres tall and weighing between 200 and 300 kilograms. It is likely to have had feathers and claws 10 to 20 centimetres long for attacking small dinosaurs, lizards and mammals, says Morrison. Had we been around then, “humans would have been perfect-sized prey, about a third of their body weight,” he says.
At the time, the Isle of Wight was still firmly attached to both mainland Britain and the rest of Europe, and the environment would have been subtropical, says Morrison. Megaraptoran fossils have been found in Asia, Australia and South America, and finding one in Europe would begin to tie their story together. Morrison suggests that _Invictibellatrix_ evolved from Asian megaraptorans that dispersed into Europe some 130 million years ago.
Then megaraptorans spread from Europe to Africa, then to South America and Australia before the continents completely separated. Jake Kotevski at Monash University in Melbourne says it is a shame more detailed comparisons couldn’t be made with _Eotyrannus_, which has previously been considered a relative of megaraptorans.
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