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Janjucetus
''Janjucetus'' ("jan-ju-see-tus", from the Jan Juc township near the type locality, and ''cetus'', Latin for whale) is an extinct genus of whale, and a basal form of the Mysticeti, a clade which includes the extant baleen whales. The only known species, ''Janjucetus hunderi'', lived during the late Oligocene, about 25 million years ago in coastal seas off southeast Australia. Unlike modern mysticetes, it possessed large teeth for gripping and shredding prey, and lacked baleen. ''Janjucetus'' was likely to have been a raptorial predator that captured large single prey animals rather than bulk-feeding on small organisms in the manner of living baleen whales.
==Description==
''Janjucetus'' is estimated to have been about in length, about the size of the modern bottlenose dolphin and much smaller than any living baleen whale. It is considered to be a mysticete due to key synapomorphies of the skull anatomy, for example in the way rostral bones meet the bones of the braincase. The relatively short snout tapers anteriorly from a broad base and is triangular in dorsal view. The incisors and canines form a terminal rosette of conical stabbing teeth, while the premolars and molars are shaped like serrated blades. The orbits are exceptionally large. No evidence shows ''Janjucetus'' possessed the ability to echolocate and probably relied on good eyesight to locate its prey.
''Janjucetus'' is considered to be closely related to ''Mammalodon'', another genus of toothed mysticetes from southeastern Australia. ''Janjucetus'' was initially assigned to its own monotypic family, Janjucetidae, but a subsequent cladistic analysis by Fitzgerald (2010) transferred it to the Mammalodontidae, making Janjucetidae a junior synonym.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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