While most parrots today are small enough to perch on your shoulder, you probably wouldn't want to do that with a newly discovered ancient ancestor of the bird. Palaeontologists in New Zealand have now uncovered the remains of Heracles inexpectatus, an extinct giant parrot that would have stood hip-high to most people and packed a beak powerful enough to crack open pretty much whatever it wanted to.

Heracles is estimated to have stood about 1 m (3.3 ft) tall and weighed up to 7 kg (15.4 lb). That makes it roughly twice as heavy as the heaviest parrot alive today – the extremely-endangered kakapo, also of New Zealand – and 10 times longer than the longest parrot, the hyacinth macaw.

The bones were discovered in a deposit in Central Otago, New Zealand, which scientists have been excavating for 20 years. Heracles has been dated to about 19 million years ago, and in its time it's believed that the bird lived in a diverse subtropical forest. There, species of laurels, palms and podocarp trees grew, which would have supplied the bird with a range of fruits to eat. But given its huge, powerful beak, the researchers say its diet could have branched out further.

"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," says Mike Archer, an author of the study. "Its rarity in the deposit is something we might expect if it was feeding higher up in the food chain."

This may be the first and so far only instance of a giant parrot, but according to the fossil record birds were often much bigger in the past than they are today. Recent finds include an enormous ostrich-like bird that stood 11.5 ft (3.5 m) tall, and a giant penguin that could have looked a human in the eye.

Interestingly, this discovery adds evidence to the idea that birds seem to consistently evolve gigantism on islands, where there may not be any natural predators. The island of Mauritius had the dodo – which was basically a giant pigeon – New Zealand had Heracles, the moa and the giant Haast's eagle, and other islands have their own giant, ancient avians.

The research was published in the journal Biology Letters.

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