The formerly used period called "Tertiary" was split into two smaller periods: Paleogene and Neogene. The term Paleogene was first used by the German geologist C. F. Naumann in 1866.

Paleogeography

In the Paleogene, the continents were close to their current-day positions. A collision between the Deccan (Indian Peninsula) and mainland Asia resulted in the Himalayan orogen. Africa migrated north, pressing onto Europe, forming the Alpine mountain chain, which includes the Carpathians.

South America also shifted northwards. Australia separated from Antarctica, opening the Drake Strait and forming a pathway for the Antarctic Circumpolar Current, thermally isolating Antarctica and causing extensive glaciation that lasts until this day.

Climate

After the warm, humid Cretaceous, the climate became cooler and drier, with occasional temperature spikes. The Antarctica glaciation around 34 million years ago accelerated this cooling trend.

Life on Earth

The reign of the mammals

The end-Cretaceous extinction led to the disappearance of most of the larger animals. Mammals, freed from the competition and predation of dinosaurs, started filling in vacant ecological niches. They increased in size and diversity, taking over land, water, and the skies.

Back to the water

Three groups of mammals independently returned to the water. Cetaceans evolved from ungulate carnivores. Dugongs (sea cows) are the most closely related to elephants and hyraxes, while pinnipeds are related to bears and weasels.

Giant birds

Large flightless birds appeared in the Paleogene: predatory Phorusrhacids ("terror birds") as part of Cariamiformes, massive herbivorous Gastornis and Dromornis with powerful beaks. Giant birds, resembling modern albatrosses, had wingspans of 6 metres!

From tropical forests to dry steppes

At the start of the Paleogene, the land was covered with lush forests and swamps. With climate cooling and drying, the forests shrank and were replaced by grassy steppes and new types of animals suited for the new environment.

Did you know ...

The largest land mammal, Paraceratherium, lived at the end of the Paleogene.

The oldest record of primates dates back to 57 million years, barely 9 million years after the extinction of dinosaurs.