A new review synthesizes what is known about crocodilians in Australasia over deep time, describing a long history in which diverse crocodylian species occupy roles as apex predators across Australia and surrounding regions. The work highlights that today’s crocodile fauna is comparatively limited relative to the variety that existed in the past, shaped by changing climates and landscapes over millions of years. The review emphasizes that the crocodiles now seen in northern Australia—such as saltwater crocodiles—are survivors from a broader, “lost world” of distinct species. It also places human arrival within the broader narrative of environmental change, noting that humans coincide with major shifts that contribute to the decline or disappearance of some species and the survival of others. Overall, the sources present crocodiles as a persistent ecological presence in the region, while also underscoring that modern populations reflect a subset of much older diversity. The summary draws on comparative knowledge from paleontology and contemporary crocodilian biology to outline what researchers understand about species persistence, turnover, and the factors behind present-day distributions.