"Leaellynasaura" is known from two nearly complete skeletons and two skulls. It is described as an ornithopod. Unlike some other ornithischians, the "Leaellynasaura" did not have any tendons in its tail. The tail is known for being among the longest of its relatives: it was three times longer than the rest of the whole body. It also has more vertebrae in its tail than any other ornithischians except for some hadrosaurs. It also had large eyes to help it look in the dark winter.