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Radioactive Dating Techniques

Corals

Carbon 14

Timeline

5 mass extenctiins

680 million years ago = first multicellular organisms (sponge)
590 million years ago = first animals with hard shells
520 million years ago = first fish
425 million years ago = first plants on land
360 million years ago = first land vertebrates
??? million years ago = first reptile
252 million years ago = permium period mass extinction
225 million years ago = first dineceor
215 million years ago = first mammal
180 million years ago = first bird
120 million years ago = first flower (angiosperms)
66 million years ago = mass extinction
50 million years ago = first modern day mammals
40 million years ago = first proto-humans
first homo-sapiens

Half Life