| GEOLOGIC TIME | |||||
|---|---|---|---|---|---|
| EON | ERA | PERIODS AND SYSTEMS | EPOCHS AND SERIES | BEGINNING OF INTERVAL* | BIOLOGICAL FORMS |
| Phanerozoic | Cenozoic | Quaternary | Holocene Pleistocene | 0.01 1.6 | Earliest humans |
| Tertiary | Pliocene Miocene Oligocene Eocene Paleocene | 5 24 37 58 65 | Earliest hominids Earliest grasses Earliest large mammals | ||
| Cretaceous-Tertiary boundary (65 million years ago): extinction of dinosaurs | |||||
| Mesozoic | Cretaceous | Upper Lower | 98 144 | Earliest flowering plants; dinosaurs in ascendance | |
| Jurassic Triassic | 208 245 | Earliest birds & mammals Age of Dinosaurs begins | |||
| Paleozoic | Permian Carboniferous Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian | 286 320 360 408 438 505 570 | Earliest reptiles Earliest winged insects Earliest vascular plants (as ferns & mosses) & amphibians Earliest land plants & insects Earliest corals Earliest fish | ||
| Proterozoic | Precambrian | 2500 | Earliest colonial algae & soft-bodied invertebrates | ||
| Archean | 4000 | Life appears; earliest algae & primitive bacteria | |||