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Australia: The Land Where Time Began |
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Spiral-Plated Echinoderms from Gondwana in the Cambrian Reveal the Earliest Pentaradial Body Plan Echinoderms are the only organisms among the animal phyla that have a pentaradial body plan and critical data on the origin of this novel organisation is provided by their fossil record as it reveals intermediate stages. In this paper the authors report on a spiral-plated animal of Early Cambrian age recovered from Morocco that is the most primitive pentaradial echinoderm discovered so far, being intermediate between helicoplacoids, a bizarre group of echinoderms with a spiral body plan, and crown-group pentaradiate echinoderms. The common pattern that underpins the body plans of the major echinoderm clades, pelmetazoans and eleutherozoans, is revealed by this fossil, which fills an important gap, showing that differential growth played an important role in their divergence. It also adds to the remarkable disparity of body plans that appeared at the time of the Cambrian Explosion.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |