Paleogene

The Paleogene Period is a time in Earth's history that lasted 43 million years, from 66 million years ago to 23 million years ago. It was the first period of the Cenozoic Era and part of the larger Phanerozoic. The Paleogene is divided into three smaller times called the Paleocene, Eocene, and Oligocene epochs.

After a big event called the Cretaceous–Paleogene extinction event, many plants and animals, including the dinosaurs, disappeared. This opened up many places for new animals to live. Many modern animals, especially mammals, began to grow and change quickly during this time. They got bigger and smaller, and some even started to fly and live in the ocean. Birds, which are the only dinosaurs left today, also started to grow and change a lot.

The Paleogene also had big changes in the world's weather. It started very warm during something called the Paleocene–Eocene Thermal Maximum, then got cooler during the Eocene, and finally, ice started to build up in Antarctica at the start of the Oligocene. This time was very important for the animals and plants we see today.

Geology

The Paleogene is divided into three series or epochs: the Paleocene, Eocene, and Oligocene. Each of these epochs has specific stages that help scientists understand and date rock layers around the world.

The Paleocene was the first epoch of the Paleogene, lasting from 66.0 million years ago to 56.0 million years ago. The Eocene followed, from 56.0 million years ago to 33.9 million years ago. Finally, the Oligocene was the last epoch, from 33.9 million years ago to 23.03 million years ago. These epochs mark important changes in Earth's climate and the types of animals and plants living during those times.

Palaeogeography

The Paleogene was a time of big changes on Earth as continents moved and oceans opened up. During this period, the last pieces of the supercontinent Pangaea broke apart. The Atlantic Ocean grew as North America moved away from Eurasia, and Australia and South America drifted from Antarctica, helping create the Southern Ocean.

Mountains also formed as Africa and India crashed into Eurasia, building the Alpine-Himalayan mountain ranges. This included the rise of the Alps, Carpathians, and the mighty Himalayas. These collisions changed the shape of the Earth and affected climate and life on the planet for millions of years to come.

Climate

Climatic conditions changed a lot during the Paleogene. After the Chicxulub impact, Earth went through a cool and dry period. Then, temperatures rose quickly during the Paleocene-Eocene Thermal Maximum (PETM). This was one of the warmest times in Earth's history, with global temperatures much higher than today.

The warming during the PETM was caused by a sudden increase in carbon dioxide and other greenhouse gases in the air. This led to warmer weather, which allowed tropical forests to grow even in cold areas. Later, the climate cooled down again, and ice sheets began to form in Antarctica. These changes affected many plants and animals, with some dying out and new ones appearing.

Flora and fauna

After the big event that ended the time of the dinosaurs, many new kinds of plants and animals began to appear. Mammals, which were once very small, started to grow and change a lot. Some of them became big land animals, while others learned to live in the water, trees, or even fly. Birds also became very common and filled the skies that were left empty after some other flying reptiles disappeared.

Plants also changed during this time. As the world got colder, tropical plants started to disappear, and new kinds of plants like grasses and herbs began to grow instead. Forests made of conifers grew in cooler, mountainous areas. These changes helped shape the world’s plants and animals as we know them today.

Main article: Flora and fauna of the Paleogene