The origin of the Metazoa in the light of the Proterozoic fossil record

  title={The origin of the Metazoa in the light of the Proterozoic fossil record},
  author={Mikhail A. Fedonkin},
  • M. Fedonkin
  • Published 31 March 2003
  • Environmental Science, Geography
Abstract Origin of the eukaryotic organisms (including the multicellular animals or Metazoa) is commonly considered to be related to growing oxygen content in the atmosphere up to a level that allows aerobic metabolism. Here it is suggested that oxygenation of the biosphere was not a permissive condition but rather a forcing factor that drove evolution towards the formation of complex biological systems. Growing concentration of free oxygen in conjunction with other geohistorical trends acted… 

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