The teeth mark the new species as a herbivore, which is unusual for such an early theropod.

Chilesaurus diegosuarezi is named in honour of Diego Suárez, who found the first bone remains in the Toqui Formation in Chile at the age of seven while out with his geologist parents. But since that first discovery, researchers have found enough additional bones – including four complete skeletons, most about the size of a turkey – to conclude that the mish-mash of parts belonged to one creature.

The dinosaurs would have had big forelimbs like the Allosaurus with two blunt fingers at the end instead of claws. But its pelvis shape, small skull and some other bones resemble totally different groups of dinosaurs, suggesting a herbivorous lifestyle that evolved in theropods independently of these other groups.

"Chilesaurus can be considered a 'platypus' dinosaur because different parts of its body resemble those of other dinosaur groups due to mosaic convergent evolution," study author Martín Ezcurra of the University of Birmingham said in a statement. "In this process, a region or regions of an organism resemble others of unrelated species because of a similar mode of life and evolutionary pressures. Chilesaurus provides a good example of how evolution works in deep time and it is one of the most interesting cases of convergent evolution documented in the history of life."

It's a reminder, he said, that researchers should be careful not to group extinct species together by similarities in form alone. Just weeks ago, another research group announced that the Brontosaurus, which had been deleted as a genus because of its apparent similarities to an earlier described one, actually has enough differences to be reinstated. It's hard to classify cousins that lived 150 million years ago, but thanks to new techniques paleontologists are getting better at it all the time.