A previously unidentified relative of Tyrannosaurus rex has been recognized from a fossil discovered on the Isle of Wight, marking the first known occurrence of a megaraptoran dinosaur in Europe. The predator, estimated to have been about the size of a tiger with long claws, has been named Invictibellatrix amberina, a name meaning "unconquered female warrior." The fossil, which had been stored in a museum collection for nearly a century, was originally found in 1924 at the base of a cliff on the Isle of Wight by amateur palaeontologist Reginald Walter Tooley.

Invictibellatrix lived approximately 120 million years ago during the Early Cretaceous period, in a region that now comprises modern-day Britain. Experts noted that had humans existed at the same time, this dinosaur would have posed a significant threat due to its size and predatory adaptations, potentially making humans "perfectly sized prey."

The newly identified species belongs to the megaraptorans, a group closely related to tyrannosaurs but distinguished by slimmer heads and large, curved claws on their forelimbs, which they used to hunt. Prior to this discovery, megaraptorans were believed to have originated in Asia, then migrated through Europe before becoming apex predators in Gondwana—an ancient supercontinent that included present-day Africa, South America, and Antarctica. However, no European megaraptoran specimens had been confirmed until this find.

The identification was made after palaeontologists revisited a fossil consisting of a fragment from the back of the skull. Researchers utilized CT scanning to create a detailed three-dimensional model of the skull portion and internal braincase structures. Comparative analysis with skulls of various related dinosaurs, including tyrannosaurs, spinosaurids, and raptors, revealed unique characteristics such as an oval opening for the spinal cord and an hourglass-shaped cranial crest, supporting the conclusion that this was a distinct species.

Invictibellatrix is estimated to have been approximately three to four meters in length and around 1.5 meters tall, roughly equal to the height of a human. Researchers also suggest the dinosaur likely bore feathers and possessed claws measuring between 10 to 20 centimeters long. The species name "amberina" references the amber deposits found in the rock formations where the fossil was located.

This discovery challenges previous assumptions about the dispersal routes of megaraptorans by providing evidence they were present in Europe and reached Gondwana through this landmass instead of island-hopping further south. The study, published in Royal Society Open Science, highlights the ongoing value of historical museum collections as reservoirs of scientific insight, with experts noting that despite over two centuries of fossil collection on the Isle of Wight, new dinosaur species, especially carnivorous ones, continue to be uncovered.