| Age | Era | Period | Epoch | Years Ago | Sample Life-Forms |
|---|---|---|---|---|---|
| Age of Mammals | Cenozoic | Quaternary Tertiary |
Holocene Pleistocene Pliocene Miocene Oligocene Eocene Paleocene |
10,000 1.6 M 5 M 24 M 34 M 55 M 65 M |
humans mastodons rhinos,camelids rabbits,hares titanotheres early horses |
| Age of Reptiles | Mesozoic | Cretaceous Jurassic Triassic |
145 M 200 M 250 M |
Tyrannosaurus rex Allosaurus Stegosaurus |
|
Age of Amphibians Age of Fishes |
Paleozoic | Permian Carboniferous Devonian Silurian Ordovician Cambrian |
300 M 355 M 420 M 440 M 490 M 545 M |
amphibians insects productids sponges, corals crinoids/sea lilies trilobites |
|
| Precambrian | 4,500 M | cyanobacteria |