| | | | | | |
| Phanerozoic Eon | present- |
| Cenozoic Era | |
| | Quaternary Period or Age | |
| | | Holocene Epoch | |
| | | | The end of the last ice age and rise of human civilization. | |
| | | Pleistocene Epoch | 11,430 |
| | | | The extinction of many large mammals and the evolution of fully modern humans. | 11,430 |
| | Tertiary Period or Age | |
| | | Neogene | |
| | | | Pliocene Epoch | 1.81 million |
| | | | | The present continents to only 70 km or so from their current locations and South America becomes joined to North America bringing a nearly complete end to the reign of South America's distinctive marsupial animals. Climates cooled, Antarctica became ice-bound and glaciations at mid-latitudes were probably underway before the end of the epoch. Both marine and continental faunas were essentially modern although land animals were recognizably a bit more primitive than today. The first recognizable primitive humanoid ancestors appeared in the late Pliocene. | |
| | | | Miocene Epoch | 5.33 million |
| | | | | Both marine and continental fauna assumed fairly modern forms with recognizable beaver, camels, crows, deer, ducks, horses, owls, whales and wolves among them. South America was not yet connected to North America and here and in Australia, widely divergent fauna existed. | |
| | | Paleogene | 23 million |
| | | | Oligocene Epoch | |
| | | | | The Oligocene starts with a major extinction event and corresponds to a sparsity of additional modern mammals which followed the evolutionary burst of the mammals during the Eocene. | |
| | | | Eocene Epoch | 37.2 million |
| | | | | The Eocene is marked by the emergence of the first modern mammals. It ends in a major extinction event which corresponds to the impact one one or more large extraterrestrial objects in Siberia and in what is now Chesapeake Bay. | |
| | | | Paleocene Epoch | 55.8 million |
| | | | | The start of the Pleocene is marked over much of the Earth by an abrupt change in flora and fauna and a discontinuity in the rocks with high levels of Iridium. A substantial, if very short lived, climatic change seems to have occurred in the early decades of the Paleocene and the majority of opinion agrees that the abrupt changes are related to the impact of a large extraterrestrial object in the vicinity of Yucatan. The modern orders of mammals emerge at the end of this period, freed from competition from reptiles. The later plant fossils of the Pleocene are attributed to modern or closely related genera and marine animals also came to resemble modern forms with only marine mammals and the Charcharinid sharks missing. | |
| Mesozoic Era | 65.5 |
| | Cretaceous Period or Age | |
| | | The end of the period corresponds with the laying down of an iridium-rich layer in the rocks which is found worldwide and thought to be associated with the Chicxulub impact crater in Yucatan and the Gulf of Mexico, which has been fairly tightly dated to 64.3 million years before the present and followed by an abrupt change in flora and fauna during the Pleocene.
The chalks of Southern England and Western Europe were laid down. | |
| | Jurassic Period or Age | 146 million |
| | | Climates were warm with no evidence of glaciation and, apparently, no land or ice-caps near either pole. The land was dominated by sophisticated dinosaurs, the seas by fish and marine reptiles. Angiosperms (flowering plants) began to appear and the first birds may have evolved. Ammonites are particularly common and diverse in the fossil record. | |
| | Triassic Period or Age | 200 million |
| | | Both the beginning and the end of the period are marked by major extinction events. | |
| Paleozoic Era | 251 million |
| | Permian Period or Age | |
| | | The end of the period is marked by a major extinction event in the fossil record. | |
| | Carboniferous Period or Age | 299 million |
| | | The period is named for the extensive coal beds deposited at the time in England (Somerset and Yorkshire) and Western Europe. | |
| | | Pennsylvanian | |
| | | Mississippian | 318 million |
| | Devonian Period or Age | 359 million |
| | | The southern continents were locked together into the supercontinent Gondwana or Gondwanaland. North America and Europe formed a single continent on the equator and the remainder of modern Eurasia lay in the Northern Hemisphere. Appearance of the Sharks (350-400 million years ago). The period is named after the county of Devon where many outcrops from the period occur. | |
| | Silurian Period or Age | 416 million |
| | | The end of the period is marked by the major extinction event where sixty per cent of marine species disappear from the fossil record. | |
| | Ordovician Period or Age | 443 million |
| | | The period was defined in 1879 by Charles Lapworth to cover the period where the division between the Silurian and the Cambrian is indistinct. | |
| | Cambrian Period or Age | 488 million |
| | | The "Cambrian explosion" - the radiation of about 50 animal phyla including almost all the basic body plans of modern animals. In most cases their precursors have not been discovered. The earliest period yielding numerous large, distinctly-fossilizable multicellular organisms more complex than sponges or medusoids. | |
