Saltriovenator zanellai was a 25-foot-long animal which weighed at least a tonne, meaning that when it lived in the early Jurassic Period, it was the largest-known carnivorous dinosaur that had ever roamed the planet.

“He was a real war machine,” said palaeontologists Cristiano Dal Sasso, Simone Maganuco and Andrea Cau, while presenting the discovery at Milan’s Palazzo Reale.

The dinosaur’s fossils were accidentally discovered in 1996 in a marble quarry near the village of Saltrio, by amateur fossil enthusiast Angelo Zanella.

It took more than two decades to extract the fossils from huge slabs of rock and to subject them to detailed analysis.

The rocks in which the fossils were contained had been blown apart by dynamite used by quarry workers, making it even harder to reconstruct them.

In the end, the paleontologists found 132 bone fragments, including pieces of the creature’s jaw, ribs, pectoral bones and a single tooth.

The dinosaur was 24 years old when it died and had somehow ended up in the sea and sunken to the ocean bed.

Marks suggest its body was feasted on by sharks and fish.