the Victorian theropod remains have been assigned to seven different clades: Ceratosauria, Megaraptora, Tyrannosauroidea, and Maniraptora. However, tyrannosauroids are not known from other Gondwanan continents, and are more known from northern Laurasia. Unlike the other Gondwanan continents whose apex predators where abelisaurids and carcharodontosaurids, the discovery of Australovenator, Rapator and an unnamed species in Australia suggests the megaraptorans were the top predators of East Gondwana. The tail vertebrae of an unknown theropod, dubbed "Joan Wiffen's theropod", were discovered in the Late Jurassic/Early Cretaceous rocks of New Zealand. Four titanosaurs–Australotitan, Savannasaurus, Diamantinasaurus, and Wintonotitan–discovered in the Winton Formation make up the sauropod assemblage of Cretaceous Australia, though, these creatures probably avoided the polar regions as their remains are completely absent in Southeast Australia which was within the South Polar region in the Cretaceous. However, it is likely that at least the titanosaurs migrated to Australia from South America, which would have required them to pass through Antarctica, since titanosaurs evolved in the Cretaceous after the break-up of Pangaea. It is possible the Bonarelli Event in the Middle Cretaceous may have made Antarctica warmer and therefore more hospitable to sauropods. These dinosaurs probably fed on the fleshy seeds of podocarp and yew trees, as well as the commonplace forked ferns of the time. Paleocene After an asteroid impact, the ensuing impact winter is thought to have killed off the dinosaurs along with much of Mesozoic life in the Cretaceous–Paleogene extinction event. However, the lack of an abrupt extinction horizon in Antarctic or Australian sediments for plant and bivalve fossils during this time period indicates a less powerful impact in the South Polar region. Given that the dinosaurs and other fauna of the polar regions of the Cretaceous were well adapted for living in long periods of dark and cold weather, it has been postulated that this community might have survived the event. Rivers and lakes The last temnospondyls–a group of giant amphibians which mainly died out after the Triassic–inhabited the South Polar region into the Early Cretaceous. Koolasuchus, perhaps the last of the temnospondyls, is thought to have survived in regions where it was too cold for their competitors, the neosuchians–a group of reptiles containing modern crocodilians–which are inactive in water below , to survive. Though neosuchians are known from Cretaceous Australia, it is thought that they stayed away from the polar region, arriving to Australia over-seas rather than over-land. It is