Which era is the oldest

The Mesozoic and Cenozoic eras make up the youngest half of the Phanerozoic. The Triassic Period, the youngest period of the Mesozoic Era, was the time in which both mammals and dinosaurs evolved.

The Mesozoic ended with a major extinction at the close of the Cretaceous Period. All dinosaurs except birds disappeared in this extinction. 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. Eras encompass major intervals of Time and are defined based on the fossil life-forms found in the rock layers, and the Law of Superposition.

There are three Geologic Eras currently identified. See illustration at right. Each of the names of the Eras reflects the relative stage in the development of life. It is also called the Age of Reptiles and the Age of Conifers. 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. And this finally happened with the Cretaceous-Paleogene extinction event at the start of the Cenozoic Era. From hominids, humans evolved in the last 4 million years of the Cenozoic era. Each segment of the Cenozoic experienced different climates.