The logic is simple. A mid-sized carnivore sees a person as a meal. A giant like Tyrannosaurus rex prefers far bigger targets. Size determines danger.

How did the researchers identify it?

Megaraptorans looked nothing like their famous cousins. Instead of massive jaws, they had narrow skulls, powerful arms and huge curved claws for seizing prey — a very different hunting toolkit.

To pin down the identity of the Isle of Wight fragment, the team used CT scanning, the same imaging technology hospitals use. The scans let them build a 3D reconstruction of the fragment and a model of its internal cavity, which once housed the brain.

Comparisons with tyrannosaurs, spinosaurs, raptors and other two-legged predators revealed unusual features. These included an oval opening where the spinal cord connected to the brain, and a distinctive crest shaped like an hourglass. Computer algorithms comparing skeletal features consistently placed the specimen within the megaraptoran group.

In short: an unknown animal, confirmed twice over.

What does it tell us about dinosaur migration?

Megaraptoran fossils are exceptionally rare, which makes the group one of the least understood among large meat-eaters. Scientists long suspected these animals first evolved in Asia, then spread through Europe before reaching Gondwana, the southern supercontinent that included present-day Africa, South America and Antarctica.

One problem dogged that theory. Europe had yielded nothing.

Co-author Charlie Scherer, a PhD student at UCL Earth Sciences, said: "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 finding suggests Europe was a key stop on the journey that carried these predators to the southern continents.

How big did these dinosaurs eventually get?

The team went beyond anatomy, using mathematical models that combined the fossil record, evolutionary relationships, ancient geography and climate to reconstruct how megaraptorans spread over millions of years.

The results suggest the group was widely distributed during the Early Cretaceous. But its fortunes shifted. By the Late Cretaceous, tens of millions of years later, megaraptorans had probably vanished from Laurasia, the northern supercontinent that included modern Europe.

In the south, they thrived. Descendants in Gondwana became some of the largest predators in their ecosystems. Some grew claws up to 35 centimeters long. One, Maip macrothorax, lived in what is now Argentina, stretched nine to 10 meters and weighed about as much as an elephant.

Why they disappeared from the north remains uncertain. The researchers point to possible culprits: climate change, shifting environments, and competition from other large carnivores such as tyrannosaurs.

What's in a name?

Plenty, in this case. Invictibellatrix means "unconquered female warrior" — a nod to the giant predators that later emerged from this lineage. In their paper, the authors say the name was chosen to "give hope and strength to all those who are bullied, discriminated, victimized, and oppressed that tomorrow will be theirs and not to give up in face of such odds."

The second part, amberina, honors amber found in the rock layers where the fossil originated and the female name Amberina.

Senior author Professor Paul Barrett of the Natural History Museum said: "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."

He added: "Work like this shows the exceptional value of working with historical museum collections where there are still many discoveries to be made."

The study drew funding from the Palaeontographical Society, the Royal Society and UKRI. The takeaway is plain: some of paleontology's biggest discoveries may already sit in museum drawers, waiting for a second look.