Janjucetus

Janjucetus
Temporal range: Late Oligocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: †Mammalodontidae
Genus: †Janjucetus
Species: †J. hunderi
Binomial name
Janjucetus hunderi
Fitzgerald 2006

Janjucetus ("jan-ju-see-tus", from the Jan Juc township near the type locality, and cetus, Latin for whale)[1] 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.[2]

Description

Restoration of Janjucetus hunderi

Janjucetus is estimated to have been about 3.5 m (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. 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.[3]

History

The only known fossil of Janjucetus was found in the late 1990s by a teenaged surfer named Staumn Hunder, near the Victorian township of Jan Juc. The name Janjucetus hunderi, honours both the township and the discoverer. Hunder is said to have seen the brown fossils on a boulder while he surfed. Soon after discovering the site, Hunder and his father removed the boulder and transported it to Monash University for further research. However, until Erich Fitzgerald started long-term research on the fossils in 2003, little had been established about the whale remains. Fitzgerald first published his findings in the journal Proceedings of the Royal Society B.[4]

The well-preserved fossil remains include a nearly complete skull, mandibles, vertebrae, ribs, scapulae, and a radius. They are held in the Museum Victoria Palaeontology Collection in Melbourne, Australia. The holotype of Janjucetus represents the most complete Paleogene cetacean fossil from Australia.

References

  1. ↑ Fitzgerald 2006, Etymology, p. 2955
  2. ↑ BBC Nature 2011
  3. ↑ Fitzgerald 2010
  4. ↑ Fitzgerald 2006

Further reading

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