Leaellynasaura was a small herbivorous ornithopod dinosaur of about 60-90 cm in length from the earliest Cretaceous, first discovered in Dinosaur Cove, Australia. It was an Australian polar dinosaur. At this period in time, Victoria would have been well within the Antarctic Circle, which is now very cold. This means that Leaellynasaura was living and apparently thriving much further south than any reptile could today. This is particularly relevant due to Cryolophosaurus being discovered in Antarctica, thus further suggesting the idea that dinosaurs could live under conditions which were once thought unsuitable for their kind. It is possible that the sun would not have risen for several weeks or months in the winter, depending on latitude, which means that Leaellynasaura would have had to live in the dark for perhaps months at a time. This is particularly relevant to the fact that Leaellynosaura had very big eyes and its brain had large optic lobes, as if it had evolved to be routinely active in the dark. Regardless, the fact that it lived in extremely cold temperatures led many scientists to believe that Leaellynasaura was warm-blooded.
No complete skeletons have been found of Leaellynasaura.