Janjucetus

Janjucetus is an extinct genus of baleen whale that lived during the Late Oligocene (Chattian) in south-east Australia, around 25 million years ago. Remains of the genus have been found in the Jan Juc Marl in the Jan Juc Formation near the township of the same name, and have been assigned to two species: the type species J. hunderi and J. dullardi. This locality has yielded remains of more extinct cetaceans, including Prosqualodon, Waipatia, and the related Mammalodon.

Unlike modern mysticetes, it possessed large teeth for gripping and shredding prey instead of baleen, and was therefore likely to have been a predator that captured individual large prey animals rather than filter feeding. However, it has been noted that the teeth of Junjucetus may have interlocked like those of the modern-day filter-feeding crabeater seal (Lobodon carcinophaga), which would have given it a limited filter-feeding capacity. At the same time the closest relative to the crabeater seal is the leopard seal (Hydrurga leptonyx), known to have had somewhat similar dentition, although its ecology mostly involves hunting larger prey, leading to the idea that Janjucetus may have fed on large fish. The animal possessed unusually large eyes, suggesting that an acute sense of vision may have aided it in hunting.