Mammalodon

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Mammalodon
Temporal range: Late Oligocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Mysticeti
Family: Mammalodontidae
Genus: Mammalodon
Binomial name
Mammalodon colliveri (type)
Pritchard 1939

Mammalodon is an extinct genus of archaic baleen whales,[1] although it lacked baleen and retained teeth.[2] It was discovered in 1932 in the Jan Juc Formation on the small Bird Rock island south of the Point Lillias peninsula in Torquay, Victoria in Australia (38°18′S 144°18′E / 38.3°S 144.3°E / -38.3; 144.3, paleocoordinates 52°54′S 142°12′E / 52.9°S 142.2°E / -52.9; 142.2).[3] It is one of two genera in the family Mammalodontidae.

Description[edit]

Mammalodon, with a length of 3 m (9.8 ft), was smaller and more basal than modern baleen whales.[4]

Mammalodon is a mix of archaeocete plesiomorphies (retained primitive traits) and mysticete synapomorphies (traits shared with more derived taxa), such as a short rostrum, reduced premaxillae, and orbits directed anterodorsally — defining features of mysticete.[5]

It had a short face and 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.

Palaeobiology[edit]

As with the closely related genus Janjucetus, Mammalodon lacked baleen, instead possessing well-developed teeth.[2] As such, it was not able to filter-feed in the same manner as extant baleen whales, making its diet and ecological niche a mystery.[2] As the teeth are widely spaced, they may have developed a method of filter-feeding unlike that of other whales. It may have been a bottom filter feeder, its blunt snout helping to suck up organisms from the sea floor.[6]

References[edit]

Further reading[edit]