Cenozoic Era

Cenozoic Era

The Cenozoic Era is the current geological era, covering the period from 66 million years ago to the present. It follows the Mesozoic Era and is characterized by significant geological, climatic, and biological changes. The Cenozoic is often referred to as the "Age of Mammals" because it is during this era that mammals became the dominant terrestrial animals.

Subdivisions

The Cenozoic Era is divided into three periods:

Paleogene Period

The Paleogene Period spans from about 66 to 23 million years ago and is further divided into three epochs:

• Paleocene Epoch (66 to 56 million years ago)
• Eocene Epoch (56 to 34 million years ago)
• Oligocene Epoch (34 to 23 million years ago)

During the Paleogene, the climate was generally warm, and the continents continued to drift towards their current positions. This period saw the diversification of mammals and birds following the extinction of the non-avian dinosaurs.

Neogene Period

The Neogene Period extends from about 23 to 2.6 million years ago and includes two epochs:

• Miocene Epoch (23 to 5.3 million years ago)
• Pliocene Epoch (5.3 to 2.6 million years ago)

The Neogene is marked by further cooling of the global climate and the development of grasslands. This period also saw the evolution of many modern mammal and bird families.

Quaternary Period

The Quaternary Period is the most recent period, beginning 2.6 million years ago and continuing to the present. It is divided into two epochs:

• Pleistocene Epoch (2.6 million to 11,700 years ago)
• Holocene Epoch (11,700 years ago to present)

The Quaternary is characterized by repeated glacial cycles and the rise of humans. The Pleistocene saw the spread of ice sheets across large parts of the Northern Hemisphere, while the Holocene marks the current interglacial period.

Climate and Geology

The Cenozoic Era has been a time of significant climatic change. The early Cenozoic was much warmer than today, but the climate gradually cooled, leading to the ice ages of the Quaternary. Tectonic activity during the Cenozoic has shaped the continents and ocean basins, with the formation of mountain ranges such as the Himalayas and the Andes.

Biological Evolution

The extinction of the non-avian dinosaurs at the end of the Cretaceous Period allowed mammals to diversify and occupy ecological niches left vacant. The Cenozoic saw the evolution of many mammalian groups, including primates, cetaceans, and ungulates. Birds also diversified significantly during this era.

Human Evolution

The Cenozoic Era is particularly important for the study of human evolution. The genus Homo evolved during the Pleistocene, with Homo sapiens emerging around 300,000 years ago. The development of human culture and technology has had a profound impact on the Earth's ecosystems.

See Also

• Geologic time scale
• Mesozoic Era
• Paleozoic Era

External Links

• University of California Museum of Paleontology: The Cenozoic Era