A dinosaur fossil that spent almost 100 years largely unnoticed in a museum collection has been identified as a previously unknown carnivorous species with large, curved claws.
Named Invictibellatrix amberina, the dinosaur lived in what is now Britain approximately 120 million years ago. Scientists estimate that it was about the size of a large tiger.
Researchers from University College London (UCL) led the investigation of the fossil, which was originally discovered on the Isle of Wight. The findings were published in the journal Royal Society Open Science.
First Evidence of a Megaraptoran in Europe
Scientists identified Invictibellatrix as the first known European representative of megaraptorans, a relatively poorly understood group of two-legged, meat-eating dinosaurs related to tyrannosaurs.
Unlike Tyrannosaurus rex, which depended largely on its powerful jaws, megaraptorans had relatively narrow skulls, strong forelimbs and prominent curved claws that may have helped them seize prey.
Over millions of years, some members of this group evolved into enormous predators comparable in size to the largest tyrannosaurs. However, Invictibellatrix belonged to the earlier, smaller members of the group.
Its name means “unconquered female warrior,” reflecting the formidable predators that megaraptorans eventually became.
Fossil Remained in Museum for Nearly 100 Years
The discovery was made from a fragment of the rear portion of the dinosaur’s skull, which entered the Natural History Museum’s collection in 1924.
Although the specimen had been preserved for decades, it received little attention until researchers examined it more closely.
Dr. Cassius Morrison, the study’s lead author from UCL Earth Sciences, estimated that the dinosaur was approximately three to four metres long and stood slightly over 1.5 metres tall.
The animal may have had feathers and possessed claws measuring between 10 and 20 centimetres.
Researchers suggest that its diet included small dinosaurs, mammals and lizards. Its ecological role may have been comparable to that of a modern hyena.
A Small Predator With Potentially Powerful Hunting Abilities
According to Morrison, a human-sized animal could have fallen within the prey range of Invictibellatrix, although humans and this dinosaur lived in completely different periods.
He suggested that the smaller predator might theoretically have posed a more direct threat to a human-sized animal than a T. rex, which could have considered such prey too small to pursue.
The comparison highlights the dinosaur’s potential hunting behaviour and does not imply that humans ever encountered the species.
Discovery Sheds Light on Megaraptoran Evolution
Megaraptoran fossils are uncommon, making it difficult for scientists to establish precisely where these dinosaurs originated and how they spread across the ancient world.
One hypothesis suggests that the group first developed in Asia before moving through Europe and eventually reaching Gondwana, the ancient southern landmass that included parts of present-day Africa, South America and Antarctica.
Before this discovery, researchers had not identified megaraptoran fossils in Europe.
Study co-author Charlie Scherer, a PhD student at UCL, said the fossil provides the first evidence of the group’s presence on the continent. It also supports the possibility that megaraptorans travelled towards Gondwana through Europe rather than dispersing between islands farther south.
CT Scans Reveal Important Skull Features
To investigate the fossil without damaging it, the research team used computed tomography (CT) scanning.
The scans produced a detailed three-dimensional reconstruction, allowing scientists to examine the internal structure of the skull fragment, including the space that once housed the brain.
Researchers compared the specimen with skulls and braincases from tyrannosaurs, spinosaurs, raptors and other carnivorous dinosaurs.
Several anatomical characteristics helped distinguish the fossil from previously identified species. These included an oval opening near the connection between the brain and spinal cord, along with a distinctive hourglass-shaped crest.
Computer-based analyses also repeatedly classified the specimen within the megaraptoran group, strengthening the case that it represented a new species.
Some Megaraptorans Eventually Reached Enormous Sizes
The researchers also investigated how megaraptorans evolved and spread over millions of years. Their analysis combined fossil records, evolutionary relationships, ancient geographical conditions and prehistoric climate data.
The results indicate that megaraptorans were distributed across several regions during the Early Cretaceous. However, they later disappeared from Laurasia, the northern landmass that included much of modern-day North America, Europe and Asia.
In Gondwana, some members of the group continued to evolve into giant predators with curved claws reaching approximately 35 centimetres in length.
One example is Maip macrothorax, which lived in what is now Argentina. Researchers estimate that it grew to around nine to 10 metres long and weighed approximately as much as an elephant.
Scientists have yet to determine why megaraptorans disappeared from northern regions. Changes in climate, shifting environments and competition with other large predators, including tyrannosaurs, are among the possible explanations.
Amateur Fossil Collector Made the Discovery Possible
The fossil was originally collected by amateur paleontologist Reginald Walter Tooley near the base of a cliff along the southwestern coast of the Isle of Wight.
Tooley gathered more than 1,000 fossils during his collecting activities, and many of these specimens eventually became part of the Natural History Museum’s collection.
Professor Paul Barrett, the study’s senior author from the Natural History Museum, highlighted the scientific importance of historical collections. He explained that specimens gathered many decades ago can still produce significant discoveries, even after spending years in museum archives.
The species name amberina refers both to amber found in the rocks associated with the fossil and to the female given name.
The researchers also intended the genus name to convey encouragement to people experiencing bullying, discrimination, victimisation or oppression.
The discovery demonstrates that museum collections can continue to reveal previously unknown species long after their fossils were first collected. It also provides new evidence about the evolution, geographical distribution and eventual disappearance of an important group of prehistoric predators.