Just a Salad, Thanks

An early vegetarian dinosaur surprises researchers

What are beaver-like incisors doing in the mouth of an animal that belongs to the theropods, a clan that includes meat-eating dinosaurs such as Tyrannosaurus rex? The Incisivosaurus gauthieri, a turkey-size addition to the growing list of new specimens from China's Liaoning Province, has led researchers to revise their expectations about dinosaur diets. No other known theropod has a set of chisel-shaped teeth like these, which are designed for gnawing plants.

The 128-million-year-old fossil is evidence that some early theropods experimented with vegetarian diets and occupied ecological niches not generally associated with this group.

Though Incisivosaurus' prominent front teeth were a complete surprise to the team that discovered the fossil, led by Xu Xing of the Chinese Academy of Sciences in Beijing and Cheng Yennien of the National Museum of Natural Science in Taichung, there are other examples of taxonomic groups with both meat-eating and plant-eating species. Among the notoriously carnivorous crocodilians are some prehistoric species with teeth designed for eating plants, and China's own giant panda has meat-eating ancestry, but now concentrates on bamboo.

—Christopher P. Sloan