Meet Chilesauraus: A Mr Potato Head dinosaur that moved from meat to veg

If you’ve ever watched a film from the Jurassic Park franchise or taken an interest in dinosaurs, you’ll know they loosely fall into two groups: aggressive, scary meat-eaters called theropods and those more chilled ones that tend to chow down on vegetation. However, dinosaurs aren’t that binary, and now scientists have found a missing link that has elements of both groups.

Researchers from the University of Cambridge and the Natural History Museum used a dataset made from more than 450 features of early dinosaurs to see where the new creature – called the Chilesaurus – fit in. Their results seemed to suggest that the Chilesaurus – discovered in Chile, as it happens – effectively sits right in the middle of the two types of dino, and could even shed light on how the split happened.

The Chilesaurus lived around 150 million years ago in the Late Jurassic period, and scientists are describing it as a kind of Frankenstein’s monster – simply because of how varied its features are. For example, it’s got a head shape much like a carnivore’s, but the teeth of a herbivore.

“Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody,” said Matthew Baron, a PhD student in Cambridge’s department of Earth Sciences and the paper’s joint author.

Scientists think the Chilesaurus is part of a group called the Ornithischia, a group of “bird-hipped” dinosaurs that include the Stegosaurus, Triceratops and Iguanodon. Usually dinosaurs in this group share two main features: a bird-like hip structure and a beak-like arrangement for eating. Scientists now believe the bird-like hip structure allowed these dinosaurs to have larger more complex, digestive systems – perfect for dissolving heavy plant matter.

And while the Chilesaurus has the same bird-hipped features as its cousins, it lacks a beak, and that makes it a significant find.

“Before this, there were no transitional specimens – we didn’t know what order these characteristics evolved in,” said Baron. “This shows that in bird-hipped dinosaurs, the gut evolved first, and the jaws evolved later – it fills the gap quite nicely.”

It looks like Chilesaurus became the Mr Potato Head of the Late Jurassic period because of a change in diet, and its adaption indicates just how quickly conditions may have worsened for meat-eaters.

“There was a split in the dinosaur family tree, and the two branches took different evolutionary directions,” said Baron. “This seems to have happened because of change in diet for Chilesaurus.