4.0 BYA – Oldest rock formation known
3.5 BYA – Earliest known life (anaerobic
bacteria)
3.0 BYA – Algae, bacteria, fungi abundant
(Stromatolites)
670 MYA – abundant jellyfish, worms,
sponges in the sea
570 MYA – Cambrian explosion
(Precambrian ends) trilobites, other hardshelled animals
480 MYA – 1st primitive fish
430 MYA – Earliest land plants (ferns and
mosses)
360 MYA – 1st insects
350 MYA – 1st land animals (amphibians)
330 MYA – Pangea together, large winged
insects, spiders, reptiles, large trees, plants
240 MYA – Pangea breaks apart, Age of
Reptiles begins
136 MYA – 1st flowering plants
65 MYA – Dinosaurs extinct
37 MYA – 1st horses, deer, bear, elephants,
cats, dogs
5 MYA – Early, primitive humans
1.6 MYA – Ice Age begins
1 MYA – Sabertooth, mammoth abundant
10,000 yrs ago – Ice Age ends
Beginning Precambrian
End Precambrian
Beginning Paleozoic
End Paleozoic
Beginning Mesozoic
End Mesozoic
Beginning Cenozoic
End Cenozoic