broad anterior face and a finger−like posteromedial projection. This finger-like process is slightly convex and would have articulated with metatarsal III. Classification The phylogenetic position of Glacialisaurus is unstable due to its fragmentary nature, but it is frequently found to be a member of the family Massospondylidae. Massospondylids are a group of non-eusauropod sauropodomorphs that existed during the Late Triassic to Early Jurassic in Africa, Antarctica, Asia, and the Americas. Massospondylids have been recovered as the sister group (most closely related group) to more derived sauropodomorphs, including Sauropoda itself, and more derived than groups like Plateosauridae. In their 2007 phylogenetic analysis of the relationships of Glacialisaurus, Smith and Pol found that it was a massospondylid. Features of its foot are similar to Lufengosaurus (from the Early Jurassic of China), and the phylogenetic study suggested that these dinosaurs were close relatives, whereas Massospondylus was found to be a more basal form. This has been supported by later analyses, including Müller (2019) which found it in a clade with Coloradisaurus and Lufengosaurus, while Massospondylus, Sarahsaurus, Pradhania, and Xingxiulong were more basal in the family. The paleontologist Oliver W. M. Rauhut and colleagues found Lufengosaurus tobe the sister taxon of Glacialisaurus in 2020, and the following cladogram shows the placement they recovered for Glacialisaurus within the sauropodomorph group Massopoda: The discovery of Glacialisaurus is important to the study of the early distribution of sauropod dinosaurs. The presence of this primitive sauropodomorph in the Hanson Formation (which has also yielded remains attributed to true sauropods) shows that both primitive and advanced members of this lineage existed side by side in the early Jurassic Period. Paleoenvironment Glacialisaurus is known from the Hanson Formation, which is one of only two major dinosaur-bearing rock formations found on Antarctica. The specimens were discovered in tuffaceous siltstone deposited in the Sinemurian to Pliensbachian stage of the Early Jurassic, dating to about 194-188 million years ago. This geological formation is part of the Victoria Group of the Transantarctic Mountains, which is approximately above sea level. The high altitude of this site supports the idea that early Jurassic Antarctica had forests populated by a diverse range of species, at least along the coast. The Hanson Formation was deposited in an active volcano−tectonic rift system formed during the breakup of the supercontinent Gondwana. Local volcanism and evidence of wildfires is known from some paleobotanical sites in the Hanson Formation. Models of Jurassic