Climate - Extinctions

Oxygen produced by photosynthetic bacteria during the Proterozoic eon accumulates in the oceans and eventually enters the atmosphere. Iron in rocks reacts with oxygen to produce rust, which turns the earth red. In this changed environment, oxygen-loving organisms evolved, while anaerobic organisms that dislike oxygen can only live in airless pockets.

Soft bodied organisms of size visible to the naked eye evolve around 900 mya and become numerous around 650 mya. By approximately 550 mya, however, they are few and far between. Few fossils of animals from this period have been found, so scientists are not certain whether they became extinct at the end of this era or evolved.

• A - Ediacaria , a radially symmetrical cast preserved on the underside of a sandstone bed, Rawnsley Quartzite,                       South Australia.
  
• B - Macro- scopic alga preserved as a carbonaceous compression in shales of Doushantuo Formation, China.
  
• C - Calcified fossils in limestones of the Nama Group, Namibia.
  
• D-  Pteridinium , a frondose Ediacaran fossil consisting of three vanes built of repeating units (two visible in specimen) that are joined along a central axis.
  
• E -  Phospatized animal egg and early cleavage-stage embryo, Doush- antuo Formation.
  
• F - Simple trace fossils of bilaterian animals,
  

Source: https://www.researchgate.net/figure/The-nature-of-the-terminal-Proterozoic-fossil-record-A-Ediacaria-a-radially_fig1_12917067