The Toolebuc Formation, exposed in Queensland, South Australia, and the Northern Territory of Australia, was deposited in a shallow sea about 100 million years ago, at the transition from the Early to Late Cretaceous. The formation is made up largely of mudstone and limestone layers laid down in what was either a protected sea or large lagoon. At the time the Toolebuc Formation was deposited, the area was further south, about 50° south latitude, similar to the Falkland Islands today. Toolebuc deposition occurred during a period of global high temperatures, so it's likely the climate was more temperate than the modern Falkland Islands.
Rocks in the Toolebuc Formation record abundant fossils of marine invertebrates, especially bivalves. Remains of terrestrial animals are present but rare. Fossils of ornithopods, ankylosaurs, and birds are present. Pterosaurs are represented by the ornithocheirid Mythunga camara and ornithocheiroid Aussiedraco molnari, both soaring fish-eaters, have been recovered. Their remains were likely washed out to sea after dying in or near a river.