New species of dinosaur discovered from fossil 'overlooked' in Natural History Museum drawer for over 100 years

Their findings, published in the journal Royal Society Open Science, were based on a partial braincase discovered on the Isle of Wight that entered the museum's collection in 1924.

"It was left in one of the collection's drawers ever since, and no one noticed it until a couple of years ago," said UCL doctoral student and study co-author Charlie Scherer.

Researchers estimated that Invictibellatrix measured about five metres long and stood just over a metre and a half tall, with a body potentially covered in filament-like feathers and fearsome claws measuring between 10 and 20 centimetres.

As one of the smaller members of the megaraptoran family, it likely preyed upon mammals, small reptiles and juvenile dinosaurs, occupying an ecological niche comparable to that of a modern hyena.

Unlike Tyrannosaurus rex, which relied on its massive skull, enormous teeth, and devastating bite force to dispatch prey while possessing famously feeble arms, megaraptorans hunted in an entirely different way.

Lead author and postdoctoral researcher at the University of Leeds, Cassius Morrison, said: "Megaraptorans are very unique among theropods because they have relatively small and slender heads but had long and strong arms with massive hand claws as well as very lightly built skeletons."

These agile predators could have pursued and caught prey with their powerful limbs and lethal claws, making them a far greater threat in a hypothetical human encounter than the legendary T. rex.

Dr Morrison said: "It was not the apex predator of its time, but for humans this dinosaur would have been more dangerous than a T Rex.

"We would have been perfectly sized prey, about a third of their body weight. They definitely would have chased us.

"A T Rex would not have bothered, as we would have been too small."

At roughly a third to a quarter of the dinosaur's body mass, a human would have constituted what Dr Morrison described as "a good hearty meal and more than just a snack," whereas the colossal T Rex would scarcely have considered such small quarry worth the effort.

The discovery fills a significant gap in scientists' understanding of how megaraptorans spread across the globe.

A prevailing theory holds that the group first emerged in Asia before dispersing through Europe, onward into Africa and eventually reaching South America, where they thrived until the asteroid impact that wiped out the dinosaurs 66 million years ago.

Until now, however, no megaraptoran fossils had been found in Europe, leaving a conspicuous gap in the evidence for this migration route.

Mr Scherer said: "These findings help to uncover the evolution of one of the most mysterious theropod groups."

The largest known megaraptoran, called Maip, reached around 10 metres in length and lived in Patagonia about 50 million years after Invictibellatrix stalked the Isle of Wight.

Amateur palaeontologist Reginald Walter Tooley originally unearthed the fossil at the base of a cliff along the south-west coast of the Isle of Wight.

Its name carries symbolic weight: Invictibellatrix translates as "unconquered female warrior," a nod to the group's trajectory from modest origins to dominant predators.

As Dr Morrison observed, megaraptorans eventually became apex hunters across South America, Australia and Antarctica, "the ruling queens", whilst tyrannosaurs reigned as "tyrant kings" in North America and Asia.

Dr Morrison added: "It is a real mystery that this fossil was overlooked for so long, sitting in a drawer for nearly 100 years."

Lots of bones are found on the Isle of Wight who knows what else is waiting to be discovered."

The research received funding from the Palaeontographical Society, the Royal Society and UK Research and Innovation.