Ediacaran

The widespread discoveries of fossil remains of Ediacaran aspect have generated continued excitement in respect of their possible evolutionary significance, and in terms of recent surrealistic interpretations of their morphology and inferred interrelationships (Pflug, 1970a,b, 1972a,b; Fedonkin, 1985 a,b; Gould, 1984, 1985; Seilacher, 1984, 1985, 1989; McMenamin, 1986; and Bergstrom, 1989, 1990), a reexamination of the actual fossil material is timely.

Swartpuntia (frondlike metazoans) and Ernietta (ribbed saclike metazoans) are part of the Ediacaran fauna.

Then in 1946, fossils of multicellular organisms were recovered from Vendian deposits around 570My old at the Ediacara copper mine in South Australia. Since then, geologists have found similar Ediacaran faunas in Precambrian rocks from other parts of the world as well.

The creature, Yilingia spiciformis — named after the Yiling district in which it was discovered — was a complicated one by the standards of the Ediacaran Period: mobile, segmented, trilobate (each body segment composed of three lobes) and bilaterally symmetrical.

Scientists who have analysed ancient fossils of Ediacaran biota – life forms that existed between 538.8m and 635m years ago – say they represent the earliest evidence of food consumed by animals.

Recently, in 2004, a new geological period, the Ediacaran, was formally added to the time scale. It immediately precedes the Cambrian period, and therefore lies within the Proterozoic.

They became prevalent during the Ediacaran, 635 to 542 million years ago.

Metazoan life was in full swing by the early phases of the Ediacaran, approximately 650 million years ago, but these first steps were small aggregations of cells with little more than eyespots or early cups of pigment lined with photoreceptive cells.

Many Ediacarans seem to have lived quiet lives of very limited mobility on the bottom of the sea.