The cambian explosion

• Cryogenian glaciation = a snowball earth just before the Cambrian explosion
• Metazoa = multicellular organisms that develop from embryos
• Ediacaran fauna = 3d soft bodied fauna that only needed 6 genetic commands
• Ediacaran demise was caused by the evolution of hard shells
• The Cambrian explosion was caused by the mineralisation after a glacial period
• Brachiopods = small shelly fosils
• Arthropods = joint and limbed animals
• After the Cambrian period came the Ordovician period, separated by extinction events
• Predators of the Ordovician period were:

  • Nautiloids - univalved and shelled
  • Conodont animals - early toothed fish
  • Eurypterids - sea Scorpians
• The Ordovician period ended with glaciation and ocean anoxia
• After the Ordovician period came the Silurian period