A frightening new species of dinosaur has been identified from a fossil found on the Isle of Wight more than a century ago. The fossil, now held by the Natural History Museum in London, belonged to a group of agile, two-legged carnivores known as megaraptorans. The discovery of the prehistoric beast, which was roughly the size of a modern tiger, is the first time a member of this group has been identified in Europe. The findings have been published in the journal Royal Society Open Science.
Unique features and naming
Megaraptorans were closely related to tyrannosaurs, including Tyrannosaurus rex, but had slender heads and relied on their powerful arms and enormous, curved claws to attack prey rather than using their jaws. Some species grew to gigantic sizes, but the newly identified dinosaur was among the smallest and earliest known members of the group. It lived in what is now the UK during the Early Cretaceous period, about 120 million years ago.
The new dinosaur has been named Invictibellatrix amberina. The name Invictibellatrix means “unconquered female warrior”, a reference to the group's later evolution into enormous apex predators. The fossil consists of part of the back of a skull. It was acquired by the Natural History Museum in 1924 but remained unstudied until now.
Size and behaviour
Dr Cassius Morrison, from UCL Earth Sciences, said the dinosaur would have measured between three and four metres long and stood just over 1.5m tall – roughly the height of a human. “Based on what we know about its closest relatives, Invictibellatrix would have been three to four metres long and just over a metre and a half in height - about as tall as a human. It would likely have had feathers and its claws might have been about 10cm to 20cm long. It would have eaten small dinosaurs, lizards and mammals – occupying a similar role in the food chain to the hyena today.”
“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,” 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.”
Scientific analysis and significance
Professor Paul Barrett, the study's senior author from the Natural History Museum, said: "Despite over 200 years of collecting, the Isle of Wight continues to surprise us with new dinosaur species, and finds of carnivorous dinosaurs, such as Invictibellatrix, have been particularly elusive. Work like this shows the exceptional value of working with historical museum collections where there are still many discoveries to be made."
Megaraptors are considered among the most mysterious large meat-eating dinosaurs because relatively few fossils have been found. Scientists believe they originated in Asia before migrating through Europe and spreading across Gondwana, the enormous southern landmass that included what are now Africa, South America and Antarctica. However, the theory had lacked key fossil evidence because no megaraptorans had previously been discovered in Europe.
Co-author Charlie Scherer, a PhD student at UCL Earth Sciences, said: “This new species is the first proof we have that megaraptorans were also present in Europe and that they reached Gondwana this way rather than island-hopping further south.”
Investigation and global spread
To investigate the fossil, researchers used computed tomography (CT) scanning to create a three-dimensional model of the preserved section of the skull and a model of the interior, including the brain cavity. They compared it with the skulls and brain cases of tyrannosaurs, spinosaurs, raptors and other two-legged carnivorous dinosaurs. A distinctive combination of features, including an oval opening where the spinal cord entered the brain and an hourglass-shaped crest, led the researchers to conclude that the fossil belonged to a previously unknown species.
Computer algorithms comparing the skull's characteristics with those of other dinosaurs also consistently placed it within the megaraptoran group. The team used mathematical modelling to explore how megaraptors might have spread around the world over time, taking into account known fossils, evolutionary relationships, geography and climate. Their analysis suggests the group was widespread globally during the Early Cretaceous, when Invictibellatrix lived. By the Late Cretaceous, tens of millions of years later, megaraptors had probably disappeared from Laurasia, the northern landmass that included modern-day Europe. In the south, however, they became apex predators across Gondwana, evolving into much larger animals with claws measuring up to 35cm (14in) long.
The study did not establish why megaraptors apparently died out in the north. Changes in climate or the environment, or competition from other predators such as tyrannosaurs, may have played a part.
Discovery and legacy
The Invictibellatrix fossil was originally found at the foot of a cliff on the south-west coast of the Isle of Wight by amateur palaeontologist Reginald Walter Tooley. It was among more than 1,000 specimens discovered by Tooley that were acquired by the Natural History Museum after his death. The researchers said the name Invictibellatrix was chosen to “give hope and strength to all those who are bullied, discriminated, victimised, and oppressed that tomorrow will be theirs and not to give up in face of such odds”. The second part of the name, amberina, refers both to the amber found in the rocks where the fossil was discovered and to the female name. The research was funded by the Palaeontographical Society, the Royal Society and UK Research and Innovation (UKRI).
