Paleontologists have unearthed a strange new species of dinosaur that is unlike anything they have seen before.
The newly described Chilesaurus diegosuarezi was an ostrich-size dinosaur that walked upright like a Tyrannosaurus rex but had the teeth of a more primitive long-necked plant eater.
"The interesting thing about this dinosaur is that different parts of it look very similar to unrelated dinosaurs," said Martin Ezcurra, a researcher at the University of Birmingham, England, who helped describe the animal Monday in the journal Nature. "It is like a combination of different dinosaurs in a single species."
This puzzle of an animal also had the thick arms of a theropod like a velociraptor, but with two blunt fingers replacing a velociraptor's sharp claws. Its pelvis is confounding too: Although researchers have determined that Chileasurus is part of the saurischia group of dinosaurs, its pelvis girdle looks more similar to one belonging to the ornithischian class of dinosaur.
"When we first found these bones, it was proposed that they belonged to different groups of dinosaurs," Ezcurra said. "It wasn't until we found a fully articulated specimen that we realized they all belonged to the same animal."
Chilesaurus is probably the descendant of meat-eating theropods and eventually evolved to become an herbivore, the researchers conclude. Plant-eating theropods have been found before, but this was the first one to be seen in South America.
Ezcurra said the dinosaur is not related to most of the animals it resembles. Instead, it developed similar traits to them in a process called mosaic convergent evolution.
"It means that two unrelated species develop similar structures because they are exposed to the same evolutionary pressures," he said.
The hybrid dinosaur lived 145 million years ago in what was once a river valley in southern Chile. Several specimens of this dinosaur have been found in the same fossil formations, suggesting that there were many Chilesaurus roaming the area at the time.
It was given the name Chilesaurus because it was found in Chile. The "diegosuarezi" part of its name is a tribute to Diego Suarez, who found the first Chilesaurus fossil in 2005 when he was just 7 years old.
Suarez was in the region with his geologist parents who were there to study rock formations. He was hunting for stones when he found his first fossil, which belonged to this strange, never-before-seen dinosaur.