Geologic Time Periods

     

What happened in each period? 
            
  Period + Age
 MYA = Million Years Ago

Period: Precambrian - Earliest
 -  1st organisms - Single Celled - Oxygen Present 
- Later - Multicelled organisms   
- 1st amphibians

Period: Cambrian - 540 MYA
- Lots of different organisms 

- Earliest animals with backbone
- lots of Carbon Dioxide 

Period: Ordovician - 490 MYA 
- Lots of animals without skeletons
- Early shell fish, trilobites, nautilus, starfish
- 1st green plant & Fungi
- End of Ice Age 

Period: Silurian - 443 MYA 
- 1st advanced plants
- Jawed Fish
- Jawed Fish with Armour
- More Shell Fish

Period: Devonian - 299 MYA - Moist climate cool 
- 1st ferns
- 1st fir trees with seeds
- 1st wingless insects
- Some animals form earlier periods die out.

Period: Carboniferous - 354 MYA
- Swampy Land
- 1st "Coal" forest (Trees)
- Coal over millions of years
- Early Sharks
- Large Trees
- 1st Reptiles + Vertebrates
- Trilobites disappearing 
- Glaciers forming
- Winged insects

Period: Permian - 290 MYA
- Land masses have formed 
- 1 continent " Pangaea" 
- Glaciers disappear - warming up
- Lots of Reptiles
- 1st Cone bearing trees
- Beetles & Flies appear
- Lots of life in Oceans
- 251 MYA - 95% life - Extinct 

- 26/10/17

Period: Triassic - 248 MYA
- Dinosaurs appear
- First Mammals crocodiles appear
- Modern corals and fish

Period: Jurassic - 206 MYA
- Lots of different Dinosaurs
- Ferns and cone bearing plants 
- Mammals common but small
- First Birds and Lizards
- Land mass, Pangaea breaks up into Gondwanaland & Laurasia 
- High carbon dioxide levels

Period: Cretaceous - 144 MYA 
- Lots of Dinosaurs including Tyrannosaurs 
- New types of insects 
- Flowering plants appear and become plentiful
- Modern Crocodiles & Sharks
- Early birds appear 
- Gondwanaland breaks up
- Rocky Mountains appear
- Carbon dioxide similar to today

Period: Paleogene - 65 - 23 MYA
- Modern Plants 
- Lots of different mammals 
- Dinosaurs are extinct 
- Primitive Whales
- First Grasses
- Rapid changes in Mammals
- Climate Cools
- Ice age begins and ends during this period

Period: Neogene - 23 - 5.3 MYA
- Modern climate
- Modern Mammals and Birds
- Horses evolve from dog like animal
- Lots of Grass
- First Apes
- Southern Alps of NZ appear

Period: Quaternary - 1.8 MYA - Present
- Anatomically modern humans
- Human stone age culture
- Ice age comes and goes
- Sahara forms from grassland 
- Humans begin agriculture
- Stone age - Bronze age 3300BC - Iron age 1120BC
- Industrial revolution leads to rise in carbon dioxide levels