GEOLOGIC TIME SCALE

• 1ST ERA - PRECAMBRIAN
• 2ND ERA - PALEOZOIC
• 3RD ERA - MESOZOIC
• 4TH ERA - CEZONOIC
• PRECAMBRIAN ERA - It is the most important events in biological

  history happened.
• PRECAMBRIAN ERA - during this era, the Earth formed, eukaryotic cells

  evolved, the atmosphere became filled with oxygen, multicellular organisms, including the first animals, evolved.
• PRECAMBRAIN ERA - history tells us that 3.5 billion years ago, the forests we have now are microscopic bacteria and algae.
• PALEOZOIC ERA - the dramatic “explosion” in diversity of

  multicellular animals and appearance of almost all living animal phyla
• PALEOZOIC ERA - the largest mass extinction wiping out

  90% of all marine species.
• PALEOZOIC ERA - divided into to six periods the Cambrian,

  Ordovician, Silurian, Devonian, Carboniferous, and Permian.