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Animal Database
Mammalodontidae
Janjucetus
Janjucetus restoration
Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Cetacea
Family †Mammalodontidae

Mammalodontidae is an extinct family of whales known from the Oligocene of Australia. There are currently two genera is this family: Janjucetus and Mammalodon. After a new cladistic analysis by Fitzgerald (2010), Janjucetus was transferred into Mammalodontidae, thereby making Janjucetidae a junior synonym of Mammalodontidae.

Genus Janjucetus[]

Janjucetus 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 3.5 metres (11 ft) 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. There is no evidence Janjucetus possessed the ability to echolocate and probably relied on good eyesight to locate its prey.

Genus Mammalodon[]

Mammalodon is an extinct genus of whale that was discovered in 1932. It is an early baleen whale which still had teeth, as opposed to baleen plates. It is one of two genera in the family Mammalodontidae. Modern whales have numerous plates with frayed edges called whalebones (or baleen). The whale ingests a mouthful of water then filters prey (such as krill) through the baleen.

Description

Mammalodon, with a length of 2.5m, was smaller and more basal than modern baleen whales. It had a short face, a delicate Premaxilla with only one or two incisors and the lateral rim of the internal auditory meatus was lengthened towards the brain case which formed a longitudinal ridge. Unlike modern baleen whales, Mammalodon was endowed with well-developed teeth.

Genera[]

Family Mammalodontidae

Janjucetus
 Janjucetus hunderi
Mammalodon
 Mammalodon colliveri

Gallery[]

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