The Ediacaran Fauna Essay

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Up until 1947, it was believed that the Cambrian Explosion marked the first true abundance of multicellular life. However, this was discovered to be untrue after Sir Douglas Mawson and R.C. Sprigg mistakenly came across numerous "fossil jellyfish" in the Ediacara Hills while observing what was originally believed to be sandstones belonging to the lowest strata of the Cambrian. At first, these finding were dismissed as "fortuitous inorganic markings."(AAS Biographical Memoirs.) Several years later however, other discoveries of segmented worms, worm tracks, and impressions of two other assemblages that bear no resemblance to any known organism, living or extinct, prompted the South Australian Museum and the University of…show more content…
Next come the elongated worm-like impressions with a horseshoe shaped head followed by 40 identical segments and rounded flattened, worm-like impressions with a central groove and strong segmentation.

These worm-like impressions belonged to the Annelida Phylum. The last two forms, which were oval shaped impressions with T shaped groves and circular impressions with three "bent arms," resemble no known organisms and are believed to represent the Phylum Arthropoda.The most abundantly distributed fossil at the South Australian site, the Dickinsonia, was represented by over one hundred specimens. These impressions may be related to some modern day flatworms and were covered with transverse ridges. The number of ridges varies with size-while smaller forms had 20 ridges, larger ones could have as many as 550. Another notable find was the Spriggina floundersi, which was named after R.C. Sprigg and Ben Flounder; the two geologists credited to their discovery.

These small annelid worms ranged between one and three inches in length and had small horseshoe shaped heads. These worms resemble the modern Tomopteridae, which have heads similar to those of the Precambrian fauna, only wider. It now appears as though these marine worms are direct descendants from the ancient forms.The Ediacaran organisms are a clear foreshadowing of one of the most dramatic events in all of life's history-the rapid expansion of shell-bearing organisms. The earth's

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