Kimberella
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Extinct (fossil)
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Kimberella quadrata is a fossil animal from the Ediacaran or Vendian fauna.
This fossil varies from 3 mm to 10 cm in size. It is oval in shape with larger ones being elongated more. The long axis has a raised ridge, and the edge is crenulated or scalloped with 44 lobes, though some always appear missing. A hump occurs in the middle axis of the fossil.
The organism this fossil represents was originally interpreted as a box jellyfish (Cubozoa). It is now believed to be a bilaterian organism, with bilateral symmetry. It has been represented as the ancestor of all bilaterian animals, however there are other Ediacaran bilateria so this is unlikely. Rather, it may be a mollusk with a non mineralised univalve shell.
Kimberella has been found in association with a trace fossil called Radulichnus, which appears to show the scrapes made by a mollusk-type radula on the sea floor. This association supports the molluscan affinities of Kimberella. There are also long trails from Ediacaran strata that may be the trace of Kimberella.
This species was first described by Glaessner and Daily in 1959. Its fossils are found both in the Ediacara Hills of South Australia and in the Ust’ Pinega Formation in the White Sea region of Russia. In the White Sea area the fossils are found with Tribrachidium, Dickinsonia, meandering trace fossil trails and algae. The strata here have been dated as 555 mya. Fan shaped scratches are found along with these fossils. This has been interpreted as marks left by a pair of hook shaped teeth on the end of a proboscis. Kimberella likely used these teeth to scratch bacteria off the surface mat on the sea bed, raking the detritus into its mouth.
The Australia Post issued a 50 cent stamp featuring Kimberella on 21 April 2005 in a series entitled "Creatures of the Slime".
[edit] References
- Glaessner, Martin and Daily, B. (1959). The Geology and Late Precambrian Fauna of the Ediacara Fossil Reserve. Records of the South Australian Museum 13: 369-401.
- Erwin, Douglas H., and Eric H. Davidson. 2002. The last common bilaterian ancestor. Development. 129, 3021-3032.[1]
