Temporal range: Early Cretaceous,118–110Ma
Rich & Rich, 1989
|Species:||† L. amicagraphica|
Rich & Rich, 1989
Leaellynasaura (meaning "Leaellyn's lizard") is a genus of small herbivorous ornithischian dinosaurs from the Albian stage of the Early Cretaceous (dated to between 118 and 110 million years ago), first discovered in Dinosaur Cove, Australia. The only known species is Leaellynasaura amicagraphica. It was described in 1989, and named after Leaellyn Rich, the daughter of the Australian palaeontologist couple Tom Rich and Patricia Vickers-Rich who discovered it. The specific name L. amicagraphica translates to "friend writing" and honours both the Friends of the Museum of Victoria and the National Geographic Society for their support of Australian paleontology.
Leaellynasaura is known from several specimens including two nearly complete skeletons and two fragmentary skulls. It has been variously described as a hypsilophodontid, a primitive iguanodontian and primitive ornithischian (Genasauria). The most recent assessment describes it as a non-iguanodontian ornithopod. Unlike more advanced ornithischians, Leaellynasaura lacked ossified tendons in its tail. The tail is noteworthy as among the longest relative to its body size of any ornithischian: the tail was three times as long as the rest of the body combined. It also has more tail vertebrae than any other ornithischians except for some hadrosaurs.
Biology and ecology
Leaellynasaura was an Australian polar dinosaur. At this period in time, Victoria would have been within the Antarctic Circle. Although this latitude is very cold today, it was less frigid in the mid-Cretaceous. However, because of the Earth's tilt, Leaellynasaura and its contemporaries would still have been living under conditions with extended periods of daylight and night. Depending on latitude, it is possible that the sun might not have risen for several weeks or months in the winter, 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 a skull fragment interpreted as being from Leaellynasaura shows enlarged eyes and the suggestion of proportionally large optic lobes, as if it had evolved to be routinely active in low-light conditions.
- Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
- Rich, T. and Rich, P. (1989). “Polar dinosaurs and biotas of the Early Cretaceous of southeastern Australia.” National Geographic Research, 5(1): 15-53.
- Federico L. Agnolin, Martın D. Ezcurra, Diego F. Pais and Steven W. Salisbury (2010). "A reappraisal of the Cretaceous non-avian dinosaur faunas from Australia and New Zealand: evidence for their Gondwanan affinities" Journal of Systematic Palaeontology, 8 (2) 
- Herne, M. (2009). "Postcranial osteology of Leaellynasaura amicagraphica (Dinosauria; Ornithischia) from the Early Cretaceous of southeastern Australia." Journal of Vertebrate Paleontology, 29(3): 33A.
- Rich, T. H. and Vickers-Rich, P. (2002). Dinosaurs of Darkness. Bloomington: Indiana University Press.
- Marthon, Antony, "Dinosaurs Down Underground", Australasian Science Magazine, Oct 2009.