PARIS // Tyrannosaurus rex, one of history’s most dreaded carnivores, had an odd-looking vegetarian cousin with a tiny head, long neck and stubby fingers.
Scientists admitted on Monday its anatomy had them puzzled.
Chilesaurus diegosuarezi had a bird-like beak with leaf-shaped teeth, evidence that it feasted on plants, but with hind leg features similar to theropod dinosaurs, the group into which it was slotted with notorious killers like T-rex, Velociraptor and the horned Carnotaurus.
“Chilesaurus constitutes one of the most bizarre dinosaurs ever found,” Fernando Novas of Argentina’s Natural History Museum in Buenos Aires said of a study published in the journal Nature which he co-authored.
“At the beginning, I was convinced that we had collected three different dinosaurs, but when the most complete skeleton was prepared, it [became] evident that all the elements pertained to a single dinosaur species.”
The bizarre creature was named after the South American country where its fossilised remains were found, and the seven-year old boy, Diego Suarez, who discovered the first bones in 2004 while exploring the Andes mountains with his geologist parents.
About a dozen Chilesaurus specimens have since been dug up.
Theropods like T-rex tended to have relatively short necks, big heads and strong, muscled hind legs larger than their arms, vicious claws and jaws brimming with razor-sharp teeth.
But Chilesaurus cuts an altogether less threatening figure.
“The proportionally small skull of Chilesaurus, with the presence of a horn beak at the tip of the snout and ... leaf-shaped teeth, reveal that Chilesaurus was a strict plant eater,” Mr Novas said.
Most skeletons discovered so far were the size of a turkey, but isolated bones have revealed that Chilesaurus could grow to about three metres in length.
Until now, herbivorous theropods were known only in close dinosaur relatives of modern-day birds, the team said. Yet the discovery of Chilesaurus showed that a meat-free diet was acquired much earlier than thought.
Chilesaurus lived at the end of the Jurassic period, some 145 million years ago – long before T-rex which ruled the plate at the end of the Cretaceous era some 70-65 million years ago.
* Agence Frane-Presse