This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The fossilized skull of a new species of mysterious meat-eating dinosaur from the Isle of Wight has been rediscovered in the collections of the Natural History Museum after over 100 years in storage. Over its nearly 150-year history, this London museum has become home to over 30 million specimens, making it easy to forget about the odd fossil or rock here and there.
This is almost definitely what happened to the only known fossil of the UK's newest dinosaur, a two-legged meat-eating theropod (the dinosaur family including birds) which we have named Invictibellatrix amberina in a new study. In 2020, Paul Barrett, one of the museum's paleontologists, looked through the fossil collections and came across a small chunk of bone which he recognized as an important part of the skull of a dinosaur: the braincase. After going through museum records, he realized the braincase was found on a beach near Sudmoor Point on the Isle of Wight, an island off the south coast of England known for its world-famous dinosaur fossils.
Knowing that it came from the Isle of Wight, Barrett enlisted one of us (Cassius Morrison), a Ph.D. student specializing in dinosaur braincases at the time, to study the fossil in detail and try to figure out which dinosaur it belonged to. This work showed that the roughly 120-million-year-old fossil was unlike anything found from the island before and belonged to a new species of a mysterious family of carnivores called the Megaraptora. Megaraptorans are known for their slender skulls, lightly built skeletons and gigantic hand claws, with some of the larger species having claws over 1 foot (30 centimeters) long.
These ferocious predators are known from across the globe, with most species known from South America, particularly Argentina. Our new British species, Invictibellatrix amberina, was on the smaller side for megaraptorans, about 5 meters (16 feet) from head to tail, and weighed as much as a large tiger, making it the smallest known megaraptoran. To study the new species, we compared it directly with the skulls of other carnivores.
This involved playing a scientific version of spot-the-difference, looking at the subtle differences between species to work out what we were dealing with. We also used computed tomography (CT) scanning, which combines X-rays and computer processing to create detailed images, to look inside the braincase of Invictibellatrix and study what we could of its brain. Putting all of these findings into a computer algorithm to determine where our species sits in the family tree helped us to avoid bias in our interpretations.
Our work suggests that the new species was probably part of the early days of megaraptoran evolution, representing what these animals looked like before they grew to gigantic sizes, similar to their relatives the tyrannosaurs. Invictibellatrix and its place in the theropod family tree are particularly important, as we now have a better understanding of when and how megaraptorans spread across the world. Before the discovery of Invictibellatrix, megaraptorans were only known from species of the early Cretaceous period (130–120 million years ago) of Thailand and Japan, plus multiple larger species from the late Cretaceous period (85–66 million years ago) of Australia and Argentina.
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