Kimberella quadrata Glaessner & Wade, 1966 in sandstone from the Precambrian of Russia. (the fossil is ~2.5 cm long)

Soft-bodied macroscopic fossils have long been known from upper Neoproterozoic (Ediacaran) rocks, but they continue to generate much excitement among geologists. Biologic interpretations of Ediacaran organisms have been all over the map. Many Ediacaran fossils appear to be animals, but some paleontologists have interpreted them as lichens or giant protists or members of an extinct kingdom.

One of the most famous of all Ediacaran fossils is Kimberella, which has been reported from South Australia and the White Sea area of Russia. It has a bilaterally-symmetrical, elongated, ovoid body with marginal concentric ridges or folds with a series of short, radiating structures. This organism was originally interpreted as a cubozoan jellyfish. It has since been considered a mollusc or mollusc ancestor or mollusc-like animal. Trace fossils associated with White Sea Kimberella specimens have been interpreted as radula scratch marks, possibly made by Kimberella (e.g., see Martin et al., 2000).

Classification: Animalia, Metazoa, Bilateria

Stratigraphy: Ust-Pinega Formation, upper Ediacaran, upper Neoproterozoic

Locality: unrecorded/undisclosed outcrop in the White Sea area, northwestern Russia

Reference cited:

Martin et al. (2000) - Age of Neoproterozoic bilaterian body and trace fossils, White Sea, Russia: implications for metazoan evolution. Science 288: 841-845. (<a href="http://web.gps.caltech.edu/~jkirschvink/pdfs/WhiteSeaAge.pdf" rel="nofollow">web.gps.caltech.edu/~jkirschvink/pdfs/WhiteSeaAge.pdf</a>)

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