An article published in the journal “Biology Letters” describes a research on Chilesaurus diegosuarezi (photo skeleton ©Evelyn D’Esposito), a dinosaur that caused perplexity among paleontologists because it looked like a T.rex’s vegetarian cousin and had other characteristics that made it a kind of jigsaw puzzle of various species. According to Matthew Baron and Paul M. Barrett this dinosaur that lived in today’s Chile about 145 million years ago is a missing link that shows how carnivorous theropods have evolved into herbivorous long-necked ornithischians.
Some bones later attributed to a Chilesaurus diegosuarezi were discovered in 2004 by Diego Suárez, who was then seven years old and was looking for decorative stones with his parents, both geologists. That discovery stimulated further research that led to the finding of other fossil bones that were initially attributed to other species. Further studies were needed to understand that the bones belonged to the same species and that its abnormal features had deceived paleontologists.
An adult Chilesaurus diegosuaresi was about 3 meters (10 feet) long and about 1 meter (3′ 4″) tall, had a teeth typical of a herbivorous dinosaur and certain adaptations of pubic bone indicate a digestive tract of a herbivorous species. On the other hand, its arms were strong and had powerful claws that allowed it to defend from other animals. Other parts of its body were typical of carnivorous theropods.
Matthew Baron and Paul M. Barrett examined over 450 anatomical characteristics of primitive dinosaurs and concluded that Chilesaurus diegosuarezi represents a missing link in the family. They’re the same researchers that in an article published in March 2017 in the magazine “Nature” described a new hypothesis about dinosaur relationships and a new classification of their groups. They and their colleague David Norman think that theropods and ornithischians had a closer relationships than it was thought so far and decided to study Chilesaurus diegosuarezi.
According to Matthew Baron and Paul M. Barrett, Chilesaurus diegosuarezi is a form of transition of ornithischians and its unique characteristics not only can help to better understand the relationships among dinosaurs but also to shed light on the evolution of the anatomical peculiarities that characterize ornithischians. If their theory is correct, there might be a whole group of dinosaurs that lived between the end of the Triassic period and the middle Jurassic we still don’t know.
The new dinosaur classification proposed by these researchers has been the source of controversy from the beginning. This study of a dinosaur with pecualiar characteristics such as Chilesaurus diegosuarezi could help to understand if that theory is correct. Surely other analyzes will follow to see if this species is really part of a group that split into two branches that took different evolutionary paths.