The new findings offer an intimate look into the evolution of a group of dinosaurs called the ornithischians.
The research, published in the Royal Society journal Biology Letters, suggested that the vegetarian dinosaur Chilesaurus, which existed about 150 million years ago, was an early member of the Ornithischia or a bird-hipped group that includes the Stegosaurus and the Triceratops.
At first, the dinosaur confused researchers due to its unique characteristics borrowed from unrelated species. For instance, it has the head of a carnivore but flat teeth seemingly designed for chewing plants.
“Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody,” said Matthew Baron, first author and Ph.D. student at University of Cambridge.
This prompted scientists to analyze more than 450 characteristics of early dinosaurs to figure out where in the family tree this creature fit well.
The Chilesaurus, for example, maintained the inverted hip structure of the ornithischians, yet it lacked the beak that other dinosaurs in this group had for eating. This could mean that in bird-hipped dinosaurs, the digestive system evolved first followed by the jaws, as illustrated by the Frankenstein dinosaur.
Dino Family Tree And Evolution
In the current dinosaur family tree, the ornithischian group was believed to be unrelated to all others. Back in March, however, a study indicated that they were more closely related to meat-eating dinosaurs than previously believed.
"Now that we think ornithischians and meat-eating dinosaurs such as Tyrannosaurus are related, Chilesaurus slots exactly in between the two groups. It is a perfect half-and-half mix,” Baron said.
Dubbed the “Baron tree,” the alternative version of the family tree also provides insight on how different dinosaur groups split from each other and evolved toward different paths. A largely controversial one, the tree is hoped by its proponents Baron and professor Paul Barrett of the Natural History Museum to eventually replace the current family tree that has existed for more than 130 years.
The evolutionary split, Baron added, could have occurred due to a change in diet for the Chilesaurus, where plant intake among some meat-eating dinosaurs proved to be an edge or a necessary tool for survival.
Barrett emphasized the Chilesaurus’ “weird mix of features” that gives it an important position in dinosaur evolution.
“[It’s] one of the most puzzling and intriguing dinosaurs ever discovered,” he said in a statement.