A fossilized braincase that sat in in the collection of the Natural History Museum in London for a century has been identified as Europe’s first megaraptoran dinosaur, a lineage once thought to have flourished mainly in the southern hemisphere.
Artists’ rendition of Invictibellatrix amberina with contemporary fauna in the lower part of the Wessex Formation. Image credit: Sergey Krasovskiy / Pedro Salas.
Named Invictibellatrix amberina, the new species belongs to a group of agile, two-legged carnivores called megaraptorans.
The animal roamed Earth during the Early Cretaceous, approximately 120 million years ago.
Its braincase came from the foot of a cliff at Sudmoor Point, near Brook, on the southwest coast of the Isle of Wight.
“It was purchased by the Natural History Museum in London from Rev. R. W. Hooley in May 1924,” said University College London paleontologist Cassius Morrison and colleagues.
“It is from the Barremian-aged strata of the Wessex Formation and has never been formally described.”
Invictibellatrix amberina’s braincase is similar in size to that of Timurlengia, a small tyrannosauroid estimated at 200 to 300 kg and no more than 4 m long, so the researchers infer that the new species was of comparable size.
Other megaraptorans are thought to have reached 6 to 10 m or more and to have weighed over 2,000 kg, which would make Invictibellatrix amberina one of the smallest known members of its group, if not the smallest.
This supports an idea that megaraptorans evolved their large body size relatively late.
“Based on what we know about its closest relatives, Invictibellatrix would have been 3-4 m long and just over a 1.5 m in height — about as tall as a human,” Dr. Morrison said.
“It would likely have had feathers and its claws might have been about 10-20 cm long.”
“It would have eaten small dinosaurs, lizards and mammals — occupying a similar role in the food chain to the hyena today.”
“It was not the apex predator of its time, but for humans this dinosaur would have been more dangerous than a Tyrannosaurus rex.”
“We would have been perfectly sized prey, about a third of their body weight. They definitely would have chased us. A Tyrannosaurus rex would not have bothered, as we would have been too small.”
The best-known members of the Megaraptora, such as Megaraptor and Australovenator, come from South America and Australia, and the earliest southern hemisphere fossils are younger than the Isle of Wight animal.
Invictibellatrix amberina fits a picture in which megaraptorans were spread across much of the world early in the Cretaceous.
The scientists suggest the group arose in Asia, reached Europe by about 130 million years ago, and later spread through Africa and into the southern continents.
“This new species is the first proof we have that megaraptorans were also present in Europe and that they reached Gondwana this way rather than island-hopping further south,” said Charlie Scherer, a Ph.D. student at University College London.
A paper describing the discovery was published today in the journal Royal Society Open Science.
_____
Cassius Morrison et al. 2026. A new megaraptoran dinosaur from the Lower Cretaceous Wessex Formation, UK, and its implications for theropod evolution and biogeography. R. Soc. Open Sci 13 (10): 260937; doi: 10.1098/rsos.260937