Cenozoic

The Cenozoic Era is the time we live in now. It started about 66 million years ago after a big event that caused many species, including the non-avian dinosaurs, to disappear. This event might have been caused by a huge space rock hitting Earth, called the Chicxulub impactor.

This era is also called the Age of Mammals because mammals became the most common land animals. Different kinds of mammals lived in different places — some in the north and others, called marsupials, mainly in Australia and parts of South America. Birds also became very successful and diversified during this time.

The Cenozoic saw big changes in Earth's climate. Early on, it was much warmer, but later it became cooler and drier, especially during the time known as the Quaternary glaciation. During this era, the continents moved to the positions we see today.

Nomenclature

The word Cenozoic comes from Ancient Greek words for "new" and "life." A British scientist named John Phillips first used it in 1840. This era is also sometimes called the Cænozoic, Caenozoic, or Cainozoic.

The Cenozoic is called "new life" because it came after the Mesozoic era, meaning "middle life," and the Paleozoic era, meaning "old life."

Divisions

The Cenozoic Era is divided into three periods: the Paleogene, Neogene, and Quaternary. It also has seven epochs: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. These divisions help scientists sort out important events from this time.

The Paleogene period began 66 million years ago after the dinosaurs went extinct. During this time, modern mammals began to appear, and the continents moved to where they are today. The Neogene period came next, when grasses spread everywhere and many new animals evolved. The Quaternary period started about 2.58 million years ago. During this time, large glaciers covered parts of the world. This period also saw humans evolve and many changes to Earth's climate and landscapes.

Tectonics

Geologically, the Cenozoic is the era when the continents moved into their current positions. Australia-New Guinea, having split from Pangea during the early Cretaceous, drifted north and collided with Southeast Asia. Antarctica moved into its current position over the South Pole. The Atlantic Ocean widened and later in the era (2.8 million years ago), South America became attached to North America with the isthmus of Panama.

India collided with Asia 55 to 45 million years ago, creating the Himalayas. Arabia collided with Eurasia, closing the Tethys Ocean and creating the Zagros Mountains, around ( https://geoltime.github.io/?Ma=35) million years ago.

The break-up of Gondwana in Late Cretaceous and Cenozoic times led to a shift in the river courses of various large African rivers including the Congo, Niger, Nile, Orange, Limpopo and Zambezi.

Climate

The early Cenozoic Era had a very warm and wet climate. Forests grew near the poles, and there was no permanent ice. Seas were higher than they are today. Over time, the climate began to cool. This happened after India crashed into Eurasia and formed the Himalayas. The cooling caused ice to build up on Antarctica. Later, when South America connected to North America and formed the Isthmus of Panama, ocean currents changed. This led to even cooler climates and the start of ice ages.

Life

After a big change on Earth long ago, small animals like mammals and birds became the main forms of life. Mammals grew and changed a lot, living on land, in water, and even in the air. Some birds, called "terror birds," grew very big and could not fly.

This time period is called the Age of Mammals because many different kinds of mammals appeared. Plants with flowers and many insects also thrived. Grasses became very important for the animals that ate them. Snakes also became more varied. The Cenozoic had many interesting animals, including whales, early primates, sabre-toothed cats, mastodons, mammoths, and giant rhinoceroses. Changes in climate and Earth's shape helped these mammals evolve.