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 made space 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 parts: the Paleocene, Eocene, and Oligocene. These parts help scientists study and date rock layers around the world.

The Paleocene was the first part, lasting from 66.0 million years ago to 56.0 million years ago. The Eocene came next, from 56.0 million years ago to 33.9 million years ago. The Oligocene was the last part, from 33.9 million years ago to 23.03 million years ago. These times show important changes in Earth's climate and the plants and animals living then.

Palaeogeography

The Paleogene was a time of big changes on Earth as continents moved and oceans opened up. During this time, the last pieces of the supercontinent Pangaea broke apart. The Atlantic Ocean grew as North America moved away from Eurasia. 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 changes shaped the Earth and affected climate and life for millions of years.

Climate

The climate changed a lot during the Paleogene. After the Chicxulub impact, Earth had a cool and dry time. Then, temperatures rose fast during the Paleocene-Eocene Thermal Maximum (PETM). This was one of the warmest times on Earth, with temperatures much higher than today.

The warming during the PETM happened because there was a sudden increase in carbon dioxide and other greenhouse gases in the air. This made the weather warmer, letting tropical forests grow in cold places. Later, the climate cooled down, and ice sheets started to form in Antarctica. These changes affected many plants and animals, with some disappearing and new ones showing up.

Flora and fauna

After the time of the dinosaurs ended, many new plants and animals appeared. Mammals, which used to be very small, grew bigger and changed a lot. Some became large land animals, while others learned to live in water, trees, or even fly. Birds became very common and filled the skies.

Plants also changed. As the world got colder, tropical plants disappeared, and new plants like grasses and herbs grew instead. Forests made of conifers grew in cooler, mountainous areas. These changes helped shape the plants and animals we see today.

Main article: Flora and fauna of the Paleogene