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). The Ediacaran[5][6] • • | Neoproterozoic (last æon of the Precambrian) Phanerozoic Axis scale: millions of years ago. ... For other uses, see Scientific classification (disambiguation). ... Incertae sedis—of uncertain position (seat)—is a term used to define a taxonomic group where its broader relationships are unknown or undefined. ... The Precambrian (Pre-Cambrian) is an informal name for the supereon comprising the eons of the geologic timescale that came before the current Phanerozoic eon. ... For other uses, see Fossil (disambiguation). ... The Ediacaran[5][6] • • | Neoproterozoic (last æon of the Precambrian) Phanerozoic Axis scale: millions of years ago. ...
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] The Edrioasteroids are an extinct class of echinoderm that lived from the Cambrian to the Carboniferous periods of geologic time. ...
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.
Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 67th day of the year (68th in leap years) in the Gregorian calendar. ...
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.
Arkarua is known only from the Ediacaran beds of South Australia.
McMenamin/Sielacher have proposed 'Arkarua' as a conventional main line member of the Vendazoa with five fold symmetry and non-iterated cell families.
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