A previously unknown species of dinosaur has been identified from a fossil originally uncovered in 1924 but overlooked for nearly a century. Named Invictibellatrix amberina, the species belonged to a group of two-legged carnivorous dinosaurs called megaraptorans, which were closely related to the lineage that included Tyrannosaurus rex.
Researchers announced the discovery in the Royal Society Open Science journal, describing Invictibellatrix as a long-clawed predator the size of a tiger, measuring between 10 and 13 feet long and standing nearly 5 feet tall. Unlike T. rex, which relied on its powerful jaws to subdue prey, Invictibellatrix likely hunted using its long arms and giant curved claws, which may have reached 10 to 20 centimeters (4 to 8 inches) in length.
The fossil—a partial skull fragment—was part of a collection of 1,000 specimens originally discovered on the Isle of Wight by Reginald Walter Tooley and later acquired by the Natural History Museum in London. The specimen remained in storage until researchers re-examined it, leading to its identification as a new species.
Physical characteristics and habitat
Based on comparisons with closely related megaraptorans, scientists estimate Invictibellatrix had a feathered body, weighed roughly the size of a large tiger, and inhabited what is now southern England during the Early Cretaceous period, approximately 120 million years ago. The dinosaur’s slender head and lightly built skeleton suggest it was an agile hunter, capable of pursuing smaller prey such as lizards, mammals, and juvenile dinosaurs.
Lead author Dr. Cassius Morrison of University College London described the species as a formidable but not apex predator, occupying a niche similar to modern hyenas. While T. rex may have ignored humans as prey due to their small size, Morrison noted that Invictibellatrix would have posed a greater threat to human-sized animals, given their preferred prey range.
Scientific significance
The discovery marks the first confirmed megaraptoran specimen from Europe, expanding understanding of how the group spread globally. Megaraptorans are distinguished by their relatively small heads, long arms, and massive hand claws, adaptations that set them apart from other theropod dinosaurs.
Researchers highlight the fossil’s 100-year dormancy as a reminder of the ongoing potential for new discoveries within existing museum collections. The specimen’s rediscovery underscores the importance of revisiting archival materials with modern analytical techniques.
Research details
The study, published in Royal Society Open Science, provides the first detailed description of Invictibellatrix’s skull anatomy among early megaraptorans. The fossil’s preservation, though limited to a partial skull, offers critical insights into the evolutionary relationships within the megaraptoran lineage.
Dr. Morrison emphasized that while Invictibellatrix was not the dominant predator of its time, its hunting methods and physical adaptations represent a unique evolutionary experiment among Cretaceous carnivorous dinosaurs.