Glacialisaurus is a genus of sauropodomorph dinosaur. It lived during the Pliensbachian stage of the Early Jurassic period around 186 to 182 million years ago in what is now the central region of the Transantarctic Mountains of Antarctica. It is known from two specimens; the holotype (name-bearing specimen), a partial tarsus (ankle) and metatarsus, and a partial left femur. The fossils were collected by a team led by paleontologist William R. Hammer during a 1990–91 field expedition to the Hanson Formation of Antarctica. They were described in 2007, and made the basis of the new genus and species Glacialisaurus hammeri. The genus name translates as “icy” or "frozen lizard”, and the species name honors Hammer. This dinosaur has been classified as a massospondylid, a group of medium-sized, basal (early diverging or "primitive") sauropodomorphs that existed during the Late Triassic and Early Jurassic on every continent except Australia. Its length has been estimated at . Glacialisaurus was a large herbivorous dinosaur, though it was average sized for a massospondylid. Glacialisaurus was distinct from other sauropodomorphs in features such as having a robust medial epicondylar ridge on the lower femur, a robust adductor ridge extending from the upper end of the femoral medial condyle, and a second metatarsal with a front border that is weakly convex in the upper end. Discovery and naming Fossils of a sauropodomorph dinosaur were discovered by a field team from Augustana College led by paleontologist William R. Hammer during 1990–91 fieldwork in the lower Hanson Formation of Mount Kirkpatrick in the Central Transantarctic Mountains of Antarctica, dating to the Early Jurassic. The fossils were from two different individuals: elements of the right ankle and metatarsus such as the astragalus, two tarsals and four metatarsals preserved in articulation (specimen FMNH PR1823), and the lower part of a left femur (FMNH PR1822, a thigh bone), ending just after the dissipation of the medial epicondylar crest. Several other fossils were collected from the same site, including fossils of the carnivorous theropod dinosaur Cryolophosaurus, a pterosaur humerus (upper arm bone), and a large tooth of a tritylodont, all found at an elevation of about . The right ankle and tarsus were preserved in a thick layer of strata, while the femur was preserved at the surface weathering next to the Cryolophosaurus specimen. The fossils were sent to the Field Museum of Natural History in Chicago, USA, and were first reported in