ARKARUA adami
Gehling, 1987
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Arkarua adami is described as one of the earliest known echinoderms. It has five-pointed symmetry (pentameral symmetry) just like living echinoderms (e.g. starfish, sea stars and sand dollars).
Localities: Flinders Ranges, South Australia Siberia Key reference: Gehling, 1987 Liu et al., 2013 |
Arkarua from South Australia.
Image: Dr Alex Liu
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Diagnosis (from Gehling, 1987):
Discoidally to hemispherically shaped echinoderm with a pentameral starshaped depression on oral surface, comprising ambulacral grooves meeting in a domed to depressed peristomial region. Theca of variable convex shape, polygonal to oval outline, surrounded by marginal rim with fine radially arranged ribs.
Discoidally to hemispherically shaped echinoderm with a pentameral starshaped depression on oral surface, comprising ambulacral grooves meeting in a domed to depressed peristomial region. Theca of variable convex shape, polygonal to oval outline, surrounded by marginal rim with fine radially arranged ribs.