Which geological era is the oldest

Devonian Period: Topic Fourth period of the Paleozoic era of geologic time between and million years ago. Jurassic Period: Topic A geological period of the Mesozoic era extending from c. Ordovician Period: Topic The second of the geological periods of the Palaeozoic era, extending from c.

Silurian Period: Topic The third of the geological periods of the Palaeozoic era, extending from c. Triassic Period: Topic A period of geological time during the early Mesozoic era, lasting from about to million years ago. Another mass extinction occurred near the end of the Triassic Period. The Cenozoic Era was a time in which communities became more modern in appearance. By the very end of the era Neogene Period , Homo sapiens , our species, had evolved. Geological Timescale The oldest fossils are between 3 billion and 3.

Paleozoic Era The Paleozoic era begins with the Cambrian radiation, a time of great growth in the number of different kinds of animals in the oceans. Norman, OK The Precambrian, Paleozoic, Mesozoic, and Cenozoic Eras The Geologic Time Scale is the history of the Earth broken down into four spans of time marked by various events, such as the emergence of certain species, their evolution, and their extinction, that help distinguish one era from another.

As nouns the difference between era and age is that era is a time period of indeterminate length, generally more than one year while age is the whole duration of a being, whether animal, vegetable, or other kind; lifetime. One of the ways history is commonly divided is into three separate periods: the Ancient Period from BC — AD , the Middle Ages from , and the Modern Era from present. Some common synonyms of era are age, epoch, and period. It has been divided into three eras: the Hadean, the Archean and the Proterozoic.

The Precambrian Era comprises all of geologic time prior to million years ago. The Phanerozoic Eon is divided into eras. From oldest to youngest, these eras are named the Paleozoic ancient life , Mesozoic middle life and Cenozoic recent life.

These time intervals are not equal in length like the hours in a day. Eras are subdivided into periods. There were a few extinctions over this period due to the changing climate but plants adapted to the various climates that emerged after the glaciers retreated. As dinosaurs roamed the Earth for over million years, we needed their dominance to end.

During the Paleozoic Era multicelled living things acquired hard body parts, bones, vertebral columns, mandibles, and teeth. Common in the Paleozoic Era were trilobites, crinoids, brachiopods, fish, insects, amphibians, and early reptiles.

The Mesozoic Era was important for the fossil remains of the dinosaurs and other reptiles that lived.