Unit Review

I wrote out a basic overview of the precambrian and phanerozoic eon that helps me generalize things hopefully it can help some other people out!

Precambrian Eon

• 88% of Earth's History
• First cells, first multi celled organisms (marine worms and jellyfish)
• Oldest rocks and fossil evidence of bacteria/cells

Phanerozoic Eon

• Paleozoic Era (Explosion of Life, life evolves in water, ozone layer is created so life can move on land)
  
• Mesozoic (Mass extinction- birds and small mammals are only to survive)
• Cenozoic (Mass extinction happened right before, allows large mammals to evolve)

More on the 3 Eras above...

Paleozoic

• Known for its explosion of life and diversity
• Earliest fish, marine animals, insects, land plants, land animals, amphibians, reptiles, sharks, trees, amnoids
• Holds 3/5 mass extinctions, one being the Permian (the largest mass extinction)
• Trilobites were abundant, but died out after this era
• Mollusks were abundant

Mesozoic

• Known as the age of reptiles. The name mesozoic means middle animals
• Holds 2/5 mass extinctions
• Earliest dinos, mammals, flowering plants, placental mammals, and birds
• Ammonoids were abundant
• Diverse bony fishes
• Dinos extinct
• Modern coral groups were present

Cenozoic

• Known as the Age of Mammals
• Modern mammals and large carnivore mammals were present (mammoths, sabertooths)
  
• Running mammals
  
• Earliest grasses
• Humans!