Arkarua
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| Arkarua Fossil range: Ediacaran |
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Arkarua is a small, Precambrian disk-like fossil with a raised center, a number of radial ridges on the rim, and a five-pointed central depression marked with radial lines of 5 small dots from the middle of the disk center. The only known species, Arkarua adami, is 3 to 10 mm in diameter. Arkarua is known only from the Ediacaran beds of the Flinders Ranges in South Australia, and takes its name from a mythical giant snake of the local Aboriginal people (Gehling 1987).
[edit] Classification
All known specimens of Arkarua are casts that give no clue to the internal structure, making classification problematic. Because of Arkarua's pentamerous symmetry, it is tentatively placed within phylum Echinodermata. Because of its flattened disk- or button-shape, some claim that it can be further classified into the Edrioasteroidea, a subgroup of the echinoderms.[citation needed]
However, it lacked a feature present in later echinoderms: the stereom, a unique crystalline form of calcium carbonate from which their skeletons are built.
[edit] External links
- Vendian animals: Arkarua from the Ediacara Hills of Australia, from the University of California Berkeley Museum of Paleontology. (pictures)
- Gehling, J.G. 1987. Earliest known echinoderm — a new Ediacaran fossil from the Pound Subgroup of South Australia. Alcheringa 11:337-345.
- McMenamin M. (1986). The Garden of Ediacara. ISBN 9780231105590. Retrieved on 2007-03-08.
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