A fossil that remained in the Natural History Museum, London’s collection for nearly a century allowed the identification of a new species of carnivorous dinosaur. Named Invictibellatrix amberina, the animal lived about 120 million years ago, in what is now the United Kingdom, and it is the first representative of the Megaraptoridae identified in Europe.
The discovery was made by a team led by researchers from University College London (UCL), who analyzed a fragment of the posterior part of the animal’s skull. The specimen had been found on the Isle of Wight, off the south coast of England, and acquired by the museum in 1924, but had never been studied in detail.
Using computed tomography, the researchers created three-dimensional models of the bone fragment and the interior of the skull, including the region corresponding to the brain. The comparison with fossils of other carnivorous dinosaurs, including tyrannosaurs and spinosaurs, revealed a distinctive combination of anatomical features that allowed the identification of a new species.
The algorithms used to compare the anatomical traits with those of other species also consistently pointed to the specimen belonging to the Megaraptoridae, bipeds known for their long arms and large curved claws.
A predator with claws up to 20 centimeters long
Based on its closest relatives, the researchers estimate that Invictibellatrix amberina would have been between three and four meters long and just over one and a half meters tall. It could have a body covered in feathers and claws about 10 to 20 centimeters long.
Its diet would probably have included small dinosaurs, lizards and mammals. Although a predator, it would not have occupied the top of the food chain in the ecosystem in which it lived, unlike some of its relatives who, millions of years later, reached much larger sizes.
The name Invictibellatrix means “unconquerable warrior” and refers to the role that Megaraptoridae would go on to play as large predators. The second element, amberina, refers to the amber found in the rocks of the region where the fossil was discovered and to the feminine given name.
A missing piece in the Megaraptoridae history
Megaraptorids are among the great carnivorous dinosaurs less known due to the scarcity of fossils. It is believed that they originated in Asia and dispersed across Europe before reaching Gondwana, the great southern landmass that included the areas currently corresponding to Africa, South America and Antarctica.
Until now, the absence of fossils of this group in Europe constituted an important gap in this hypothesis. The identification of Invictibellatrix amberina provides the first fossil evidence of the presence of these animals on the continent and supports the possibility that they reached Gondwana via Europe, rather than following a more southerly route, between islands.
The investigation also suggests that megaraptorids had a broad geographic distribution during the Early Cretaceous, but disappeared from northern regions, including Europe, tens of millions of years later. In the Late Cretaceous, they continued to be apex predators in Gondwana and some species reached gigantic dimensions, with claws up to 35 centimeters long.
The study does not clarify why the group disappeared from northern regions. Among the hypotheses considered are climate and environmental changes and competition with other predators, including different groups of tyrannosaurs.
Museums still guard discoveries waiting to be made
The fossil was found near the base of a cliff on the southwest coast of the Isle of Wight by amateur paleontologist Reginald Walter Tooley. After his death, the Natural History Museum acquired more than a thousand specimens discovered by Tooley, among which was the fragment now identified.
For the authors, the discovery demonstrates the scientific potential of museum historical collections, where specimens collected decades or centuries ago can continue to yield new information about the evolution and distribution of prehistoric animals.
The study was published in the scientific journal Royal Society Open Science and was funded by the Palaeontographical Society, the Royal Society and UK Research and Innovation (UKRI).
