Microdictyon.jpg



The Ediacaran fauna are fossilized multi-cellular organisms that were formed by moving sands washed over mud flats, thus creating these impressions.



Ediacaran Fauna

Existed from 600 million years to 545 million years ago, the fossils are a Precambian assemblage. These fossils are ancient lifeforms that represent the earliest known multicellular organisms. They appeared after the Earth thawed from the Cryogenian period’s extensive glaciers, and disappeared just before the appearance of biodiversity - the Cambrian explosion.

The fossils are in many different morphological characteristics:
Embryos - Recent discoveries show that Embryos dominated Precambrian multicellular life
Discs - These are circular shaped fossils which led to the initial identification of Ediacaran fossils as cnidaria , which include jellyfish and corals.
Bags - They are preserved within sediment layers and it yet a long way from reaching a concensus of the science commnunity's interpretation
Quilted organisms - Considered to be Vendobionta which resembles a "quilted" appearance.
alacarte.jpg
Fossil sites - significant time scale and map of the animals evolved over time including the Edicaran Fauna 500 m.y.a.

History of the Ediacaran fauna

First discovered in 1946 by R.C. Sprigg and Sir Douglas Mawson in South Australia, these fossils marked our evolutionary view on life. Prior to the discovery, everyone believed that there was no multi-cellular life before the Cambrian explosion. The earliest fossils found (dating back to around 1,000 million years after the world was first created) were single-celled organisms. Fossils towards the end of the Precambrian time period and close to the beginning of the Cambrian explosion show signs of multicellular life. At the end of the Precambrian time period, all Edicarian fauna went extinct bar 4% of them.

Evolutionary Significance

"Macroscopic fossils of soft-bodied organisms can be found in a few localities around the world, confirming Darwin's expectations." [1] It is believed that the oldest animal fossils are trilobites and brachiopods, which are approximately 540 million years old, but many Paleontologists believe that there should be much older (simpler) fossils but there were no exidence to confirm it.

Bibliography




Berkeley UCMP. Introduction to the Vendian Period. J.W. Valentine and J.H. Lipps.
     Retrieved June 13, 2007, from http://www.ucmp.berkeley.edu/vendian/vendian.html
 
Museum Victoria. (2005). The History of Earliest Life. In //Museum Victoria//.
     Retrieved June 13, 2007, from http://www.museum.vic.gov.au/dinosaurs/
     lifetime-early.html
 
Wikipedia. (2007). Ediacaran biota. Wikipedia.
     Retrieved June 13, 2007, from http://en.wikipedia.org/wiki/Ediacaran_biota