The theropod (“beast-footed”) dinosaurs, which included Tyrannosaurus rex and other fierce predators, were notorious carnivores that lived between about 230 million and 66 million years ago. A few theropods did eventually become vegetarians, however, although only toward the end of this dino group’s long reign. Now, paleontologists working in southern Chile report the surprising finding of an early vegetarian theropod, which they call Chilesaurus diegosuarezi (pictured here in an artist’s reconstruction), dated to 150 million years ago. The critter, a nearly complete skeleton of a juvenile about 1.5 meters long (and which would have been about twice as long when fully adult), was named after Chile and also in honor of Diego Suarez, a 7-year-old boy who first discovered the fossils in Chile’s dino-rich Toqui Formation. As the research team reports online today in Nature, it was at first confused about how to classify the new dino, because its skeleton contained features typical of several different dinosaur types including carnivores and at least two kinds of plant eaters. Thus, it had a long neck and leaf-shaped teeth typical of many veggie dinos, but the structure of its vertebrae and hips were more like those of the theropods. Yet when the team performed a detailed statistical analysis of C. diegosuarezi’s overall features, the animal consistently grouped with the theropods. This odd mixed bag of characteristics makes C. diegosuarezi “an extreme case of mosaic evolution among dinosaurs,” the team writes, and suggests that even some of the earliest meat eaters might have turned to vegetarianism as an alternative lifestyle.
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