Cenozoic Era

The Cenozoic era, also known as the era of mammals, is the most recent and last subdivision in the animal history. The term Cenozoic means new life, which is derived from the Greek words Kainos for new and zioc for life. According to the geological timescale, this era spans the period from 65 million years ago to the present. The oldest subdivision is the Paleozoic (543-248 million years ago) followed by Mesozoic era (248-65 million years ago).

The Cenozoic era consists of two periods - the Paleogene and Neogene. The former encompasses three epochs, namely, Paleocene, Eocene and Oligocene; whereas, the latter is divided into four epochs - Miocene, Pliocene, Pleistocene and Holocene. The Holocene epoch is ongoing. In previous times, Cenozoic era was divided into two sub-eras, the Tertiary and Quaternary. The Tertiary included the time span from 65-1.8 million years ago (Paleocene till Pliocene epochs), whereas the Quaternary covered only the recent 1.8 million years ago (Pleistocene and Holocene epochs) till the present.

Cenozoic Era: Climate

The climate in the beginning of the Cenozoic era was more or less similar to the present climatic conditions. In comparison to the Mesozoic, the climate has cooled down significantly during Cenozoic era. Scientific evidences have revealed that long-term cooling occurred from the Pliocene, after the completion of Miocene epoch. The global climatic change is evident from the fossils of angiosperm leaves; entire margin indicates warm climate, whereas serrated or toothed margin represents cool climate.

The plate tectonics (movement of continental plates) continued to occur during Cenozoic era, which actually started in the Mesozoic era. As a result of plate tectonics, large continental plates moved towards the pole, which in turn, allowed the entry of warm tropical waters in the polar areas. Gradually, the ice age began and the continents were transformed into the modern forms of today. The Atlantic ocean, which was previously a small valley widened into a vast ocean. Along with this, the Himalayas, the Rocky and Andes Mountains were formed during Cenozoic era.

Cenozoic Era: Plants and Animals

Modern species of flowering plants were evolved at the beginning of the Neogene period. A wide variety of small, non-woody plants as well as herbs also evolved in the late Neogene, hence this period is also referred to as the age of herbs. Grass evolution played a significant role in the ecosystem by serving as food for birds and other land mammals.

Speaking about dominant animals of the Cenozoic era, the enormous Mesozoic dinosaurs became extinct. Some of the land animals evolved in this era include giant rhinoceros, elephants, lions, sabre-toothed cats, deer, hyenas, giraffes, camels, horses, dogs, cats, pigs, snakes, birds and bats. In the seas and oceans, whales, giant sharks (about 42 feet), dugongs, coral, echinoids and gastropods were dominant. Insects and termites were believed to evolve in the Eocene epoch. Simultaneously, similar to other subdivisions, many became extinct during the Cenozoic era.

Cenozoic Era: The Age of Mammals

It is to be noted that mammals evolved long before the Cenozoic era. However, the early mammals were small and generalized forms that resembled mouse. It was only during the Cenozoic era that the largest and more diverse mammals (bats, whales) were evolved. Hence, the name, age of mammals is alternatively used. Over a period of time, many giant species of mammals became extinct.

To mention a few, large extinct mammal species include woolly mammoth (about 12 feet), woolly rhinoceroses, cave lions, cave bears, sabre-toothed cats, giant birds (2 meter height) and giant deer. Regarding the evolution of humans, it is believed that early forms of humans evolved in Africa during the Miocene epoch. The ancestors of human beings or homo sapiens became dominant about one million years ago.