A giant “cannibal” parrot which roamed the Earth 19 million years ago has been discovered by scientists.

Dubbed Hercules, the one-metre-high bird is the largest parrot ever found, and twice the size of the largest species alive today.

Analysis of a fossil discovered in what was once a Miocene epoch forest in New Zealand indicates the 7kg bird had a huge beak, able to crack into and break down most food sources, including other parrots.

The fossil is approximately the size of the giant “dodo” pigeon, which went extinct in the Seventeenth Century.

The discovery was made by experts at Flinders University, The University of New South Wales Sydney, and Canterbury Museum in New Zealand.

They have have formally named the species Heracles inexpectatus, to reflect its Herculean size and strength, as well as the unexpected nature of the discovery.

Professor Mike Archer, from UNSW Sydney, said: “Heracles, as the largest parrot ever, no doubt with a massive parrot beak that could crack wide open anything it fancied, may well have dined on more than conventional parrot foods, perhaps even other parrots.

The ancient parrot would have competed with all manner of species on the forest floor Credit: Flinders University

“Its rarity in the deposit is something we might expect if it was feeding higher up in the food chain.

“Parrots in general are very resourceful birds in terms of culinary interests.”

Birds have repeatedly evolved giant species on islands."

As well as the dodo, there has been another giant pigeon found on Fiji, a giant stork on Flores, giant ducks in Hawaii, giant megapodes in New Caledonia and Fiji, giant owls and other raptors in the Caribbean.

Published in the Royal Society journal Biology Letters, the analysis of the bones found near Central Otago, describes how Heracles lived in a diverse subtropical forest among many species of laurels, palms and podocarp trees.

“Undoubtedly, these provided a rich harvest of fruit important in the diet of Heracles and the parrots and pigeons it lived with,” said Professor Suzanne Hand, also from UNSW Sydney.

A colleague added: “The St Bathans fauna provides the only insight into the terrestrial birds and other animals that lived in New Zealand since dinosaurs roamed the land more than 66 million years ago,”

In the same excavation area paleontologists have also found evidence of crocodilians, turtles, a number of bat species as well as more than 40 types of birds.