Dipleurozoa

Dickinsonia is a genus of extinct organism that lived during the late Ediacaran period in what is now Australia, China, Russia, and Ukraine. It had a round, approximately bilaterally symmetric body with multiple segments running along it. It could range from a few millimeters to over a meter in length, and likely lived in shallow waters, feeding on the microbial mats that dominated the seascape at the time.

Windermeria aitkeni (named after Windermere, British Columbia, Canada) is a Precambrian organism from the Blueflower Formation of Sekwi Brook North, in the Northwest Territories of Canada. Only one specimen has been found. Windermeria is a small (16.4 × 7.9 mm) segmented elongated oval fossil with eight nearly equal-sized segments arranged transverse to medial furrow in opposite arrangement. Windermeria superficially resembles a diminutive Dickinsonia and as such is the only possible dickinsoniid proarticulatan known exclusively from outside of Australia and East Europe.

Dipleurozoa (or Dickinsoniomorpha) are extinct proarticulate organisms of the Ediacaran period, which had a flat and more or less ovoid shape. Polychaete worms were treated, however it seems more likely that they were vendobionts. The most representative genus is Dickinsonia, which gives the name to the class (in the case of Dickinsoniomorpha).