A museum drawer hid Europe’s first megaraptor, a tiger-sized T. rex cousin

A piece of dinosaur skull that sat in a London museum drawer for nearly a century belongs to a predator nobody had named, from a group nobody had ever found in Europe. The animal, now called Invictibellatrix amberina, was a megaraptoran: a two-legged hunter closely related to tyrannosaurs that seized prey with long arms and huge curved claws instead of crushing it with its jaws.

That matters because megaraptorans are among the hardest meat-eating dinosaurs to place on the map. Paleontologists suspected they began in Asia and crossed Europe to reach the southern continents, where some grew as heavy as an elephant. Europe, though, had never produced a fossil to prove the route. A single braincase from the Isle of Wight now fills that gap.

The fossil comes from the Wessex Formation, the dinosaur-rich rocks of the island’s south-west coast, and dates to the Early Cretaceous, about 120 million years ago. A team led by Cassius Morrison of University College London, with senior author Paul Barrett of the Natural History Museum, describes it in the open-access journal Royal Society Open Science. Their analysis places Invictibellatrix as a small, early member of Megaraptora, only distantly related to every theropod previously named from the same rocks.

The lead author gives the animal a human scale. In Morrison’s words: “Based on what we know about its closest relatives, Invictibellatrix would have been three to four metres long and just over a metre and a half in height – about as tall as a human. It would likely have had feathers and its claws might have been about 10cm to 20cm long.”

How one braincase can name a new dinosaur

The specimen, catalogued as NHMUK PV R6775, is the back of the skull: the bony box that held the brain and the opening where the spinal cord entered it. That sounds like an unpromising place to look for an identity. Theropod braincases have a reputation for being conservative, so alike across groups that they say little about family ties. The team argues the opposite, writing that braincase characters provide essential data for sorting out how theropods are related.

The researchers CT-scanned the fossil, which let them build a three-dimensional model of the bone and a second model of the empty space inside it, the cavity that once housed the brain. A scan sees internal canals and surfaces without cutting or cleaning a fragile, century-old specimen any further. They then compared the anatomy with braincases of tyrannosaurs, spinosaurs, raptors and other two-legged meat-eaters.

Three features stood out: a nearly circular occipital condyle, the knob where the skull meets the neck; an oval foramen magnum, the hole through which the spinal cord entered; and an hourglass-shaped crest along the back of the skull. That combination matches no named species. When the team ran phylogenetic analyses, computer programs that build family trees from shared traits, the specimen landed inside Megaraptora each time.

A tiger-sized cousin of T. rex, built for small prey

Megaraptorans are among the least understood large carnivorous dinosaurs because their fossils are so rare. They had narrow skulls, powerful arms and, in later southern species, claws up to 35 centimeters long, longer than a school ruler. The giants of the group, such as Maip macrothorax from Argentina, are estimated at nine to ten meters long and as heavy as an elephant.

Invictibellatrix sat at the other end of that range. At three to four meters it was about the size of a large tiger, and Morrison compares its place in the food chain to a hyena’s. It ate small dinosaurs, lizards and mammals and was not the top predator of its world; the museum’s reconstruction of the scene gives that role to a fish-eating spinosaurid.

Its modest size is why Morrison argues it would have been more dangerous to a person than T. rex. In the lead author’s words: “We would have been perfectly sized prey, about a third of their body weight. They definitely would have chased us. A T. rex would not have bothered, as we would have been too small.” The comparison is a thought experiment, since humans and non-avian dinosaurs missed each other by more than 60 million years.

The European stop on the road from Asia to Gondwana

The larger payoff is geographic. The leading story for megaraptorans has them originating in Asia, moving through Europe and then spreading across Gondwana, the southern supercontinent that included present-day Africa, South America and Antarctica. Without a European fossil, other routes stayed on the table.

According to co-author Charlie Scherer, a PhD student at UCL Earth Sciences, “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.”

The team also built a biogeographical model that combines the known fossils, the family tree, ancient geography and climate. It suggests early megaraptorans were spread across much of the world in the Early Cretaceous. By the Late Cretaceous, tens of millions of years later, they had probably vanished from Laurasia, the northern supercontinent that included Europe, while in the south they became apex predators. The paper concludes that their absence in the north is best explained by regional extinction.

What one braincase cannot settle

The whole species rests on a single bone. Everything about the living animal beyond the braincase, from its length and height to its feathers and claws, is inferred from its closest relatives rather than measured. Morrison frames the size in exactly those terms, and a skeleton found later could move the estimates in either direction.

The family-tree placement carries its own uncertainty. The analysis puts Invictibellatrix near the base of Megaraptora, among a loose set of Eurasian forms that do not form one tidy branch. Early members of a group are where new fossils most often redraw the tree, so one more find from Asia or Europe could shuffle its neighbors.

Nor does the study explain why megaraptorans disappeared from the north. The researchers suggest shifts in climate or environment, or competition from other large predators such as tyrannosaurs, but the model shows where the group vanished, not why.

A century in a museum drawer

The fossil was found at the foot of a cliff on the Isle of Wight’s south-west coast by an amateur collector. The Natural History Museum acquired it in 1924 as part of a collection of more than 1,000 specimens bought after his death, and it was overlooked for study until now. The material was first flagged in a conference abstract in 2024, and the formal description was published on October 14, 2026.

For Morrison, “It is a real mystery that this fossil was overlooked for so long, sitting in a drawer for nearly 100 years.” Barrett sees it as a lesson about old collections: “Despite over 200 years of collecting, the Isle of Wight continues to surprise us with new dinosaur species, and finds of carnivorous dinosaurs, such as Invictibellatrix, have been particularly elusive.”

The name means “unconquered female warrior,” a nod to the giant predators the lineage later produced. In the paper, the authors write that it is meant to “give hope and strength to all those who are bullied, discriminated, victimised, and oppressed that tomorrow will be theirs and not to give up in face of such odds.” The species name, amberina, refers to the amber found in the rocks where the fossil came from and to the female name Amberina.

Common questions about Invictibellatrix

What is a megaraptor?

Megaraptorans are a group of two-legged meat-eating dinosaurs closely related to tyrannosaurs. Instead of relying on massive jaws, they had narrow skulls, strong arms and large curved claws for seizing prey. Most known fossils come from the southern continents, and the largest species reached nine to ten meters long.

Was Invictibellatrix bigger than T. rex?

No. Based on its closest relatives, it was about three to four meters long and roughly as tall as an adult human, around the size of a large tiger. T. rex was several times longer and far heavier, which is why the lead author argues a human would have been the right size of prey for Invictibellatrix but not for T. rex.

How old is the Isle of Wight megaraptor fossil?

The braincase comes from the Wessex Formation and dates to the Barremian stage of the Early Cretaceous, about 120 million years ago. That makes Invictibellatrix one of the earliest megaraptorans known.

Is Invictibellatrix the first megaraptor found in Europe?

Yes. The study describes it as the first megaraptoran identified in Europe. Before it, the group was known from Asia and from the southern continents, which left a gap in the proposed route between them.

The holotype remains in the Natural History Museum’s collections, open to any researcher who wants to test the new placement, and the paper is free to read. Morrison expects more: “Lots of bones are found on the Isle of Wight – who knows what else is waiting to be discovered.”

Reference: Morrison et al., “A new megaraptoran dinosaur from the Lower Cretaceous Wessex Formation, UK, and its implications for theropod evolution and biogeography,” Royal Society Open Science, 2026. DOI: 10.1098/rsos.260937

Tags: dinosaurs, New species, paleontology, Invictibellatrix, Isle of Wight, Megaraptora