Type species: Tianyulong confuciusi
Location: Western Liaoning Province, China
Tianyulong belongs to a group of early ornithischian dinosaurs called heterodontosaurids, a group problematic to classify (as it is often classified with ornithopods or a stem group of ornithischians) and long have been known from Early Jurassic species in Africa. This means that Tianyulong is not only the youngest known heterodontosaur, but it is also the only known heterodontosaur in Asia. The skeleton shows strange filament-like features along parts of its body, largest around its back and tail. These structures resemble the primitive feathers seen on some theropod dinosaurs, making Tianyulong the first known ornithischian with feathers. Still, it verifies another theory. In the Yixian Formation, preserved skeletons of Psittacosaurus show long bristles on its tail. Many scientists argue that these were modified feathers. The discovery of a feathered ornithischian provides some evidence for this idea.