Scientists were initially confused by this dinosaur because it had weird phsyical characteristics that appeared to come from two separate groups of dinosaurs.
A freaky dinosaur which looked like a raptor but was in fact a vegetarian may be the "missing link" between plant-eating dinosaurs and theropods, the group that includes carnivores such as Tyrannosaurus rex and Velociraptor.
Baron's team analyzed data from more than 450 anatomical characteristics of early dinosaurs to place the Chilesaurus on the ancient reptiles' family tree - and as they explained in a statement, it not only effectively fills a large gap between two of the major dinosaur groups, but also seems to explain how the divide between those two groups may have happened in the first place. It may even show how the split took place.
"Chilesaurus is nearly like a velociraptor in terms of its height, length and overall build", Matthew Baron, of the University of Cambridge, said.
"Chilesaurus is one of the most puzzling and intriguing dinosaurs ever discovered", said study co-author Paul Barrett, of the Natural History Museum in London.
The first fossils of Chilesaurus diegosuarezi were found in 2004 in southern Chile by a seven-year-boy, Diego Suarez, after whom the species was named.More news: Sessions: Charlottesville Car Attack Could Be Civil Rights Violation, Hate Crime
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The odd-looking dinosaur lived during the Late Jurassic period, about 150 million years ago, and features a carnivore-like head but flat teeth for grinding up plant material.
Unlike prior research which proposed this dinosaur was part of the so-called "Lizard hips" group known as Therapoda, the new research suggests it came from a different group known as Ornithischia.
Matthew Baron from the Cambridge Department of Earth Sciences and his Natural History Museum colleagues are behind the new study.
One of the particularities of ornithischia group dinosaurs is their hip structure, which allowed them to have complex digestive systems.
"Now that we think ornithischians and meat-eating dinosaurs such as Tyrannosaurus are related, Chilesaurus slots exactly in between the two groups". And that fills in an important missing link between two of the major dinosaur groups, and helps scientists understand how the two might have split. That makes it a significant find, the researchers say.
Scientists didn't know in which order the ornithischia group's characteristics evolved because, it's believed, this group of dinosaurs was the first transitional specimens. Based on the team's analysis, it looks like the gut of this dinosaur evolved before the jaw, for example.
Earlier this year, the same group of researchers argued that dinosaur family groupings need to be rearranged, re-defined and re-named. "This seems to have happened because of change in diet for Chilesaurus". In turn, this might have led to the appearance and evolution of larger plant-eaters.