Earth and Moon

The Neogen: Miocene and Pliocene

The Neogen: Miocene and Pliocene

Neo is the second of the three periods in which the Cenozoic Era. It started 23 million years ago, it ended 2.59 million years ago and it is the time of apes and hominids.

Formerly the Paleogene and Neogene periods used to be grouped as "Tertiary" or even "Tertiary Era". He Neogenic Period it was known as Tertiary upper with limits somewhat different from those accepted today.

The Neogen: mammals, birds, grass and hominids

Mammals and birds developed quite during this period. The weather, moderate at the beginning, cooled down. At the beginning of the Neogen the apes appeared and, towards the end, the hominids. Hi!

The Neogen is distributed in two epochs, Miocene and Pliocene. However, there is a proposal from the International Stratigraphy Commission (ICS) that intends to add the Pleistocene and the Holocene, which currently form the Quaternary and that reaches the present.

•" He Miocene It started 23 million years ago and ended 5.3 million years ago. The weather was cooler and drier than in the previous era because a large ice cap formed in Antarctica that accumulated moisture.

All over the planet, large areas that were previously covered by thick forests became grasslands. In the arid zones a new vegetation appeared, the chaparral. The forests began to make clear where the grass grew. Herbaceous plants were better adapted to the climate of this period, which could well be called The Herb Age.

The mammalian fauna of the Miocene contemplates the appearance of the mastodon, the raccoon, the weasel, the hyena and the bears. There were rhinos, cats, camels and horses in their primitive forms. Great apes, related to the orangutan, lived in Africa, Asia and southern Europe. The first hominids began to evolve in East Africa.

In the seas the whales, the define, the sharks and the seals progressed. Thanks to the decline of the forests, some small animals, such as rodents, frogs, snakes and birds, were very successful.

The elevation of the great mountain ranges, initiated during the Oligocene, went ahead, having just shaped the Alps in Europe, the Himalayas in Asia and the mountain ranges of the American continent. The sediments produced by the erosion of these systems were deposited in shallow marine basins, to end up converted into rich oil deposits in California, Romania and the west coast of the Caspian Sea.

The eastern entrance of the Tethys Sea closed between 19 and 12 million years ago, when Africa collided with Eurasia in the Middle East. Then mountains rose in the western Mediterranean. All this, together with the descent of the sea, caused the Mediterranean to dry at the end of the Miocene. This phenomenon is known as the Saline crisis of the Messinian.

These events had another effect: by opening land routes, many animal species were able to migrate and spread to other areas, which had a great impact on the fauna of Africa, Eurasia and North America.

•" He Pliocene It extends from 5.3 million years ago to 2.59 million years ago. In western North America, subduction of the Pacific tectonic plate contributed to the elevation of the Sierra Nevada and the Cascades volcanic mountain range. In Europe, the Alps continued their ascent supported by the movement of plate tectonics that pushed and combed the crust in a wide region of this continent.

He isthmus of Panama, formed by colliding South America with North America, led to the disappearance of the ancient South American marsupial fauna. In addition to joining the lands, the isthmus separated the Atlantic and Pacific oceans, cutting off the warm equatorial currents. As a result, both oceans cooled, especially the Atlantic and, especially, the Arctic and Antarctic waters. The polar caps continued to accumulate ice.

The decline in sea level revealed a land bridge between Alaska and Siberia (now Bering Strait), which facilitated migration. Thus, all continents were united, except Australia, Antarctica and the islands. Britain was still a peninsula of Europe.

At the end of the Miocene, the Betic-Rifeño system had been formed and the passage between the Atlantic and the Mediterranean was cut. This sea dried up, the weather became arid and large amounts of salts were deposited. At the beginning of the Pliocene, the Strait of Gibraltar was opened and the Mediterranean was filled again.

The coldest and driest climate reduced tropical plants to a narrow equatorial strip. Also, having the Earth seasons very marked, the deciduous trees increased. Coniferous forests and tundra occupied the cold areas, while grasslands colonized large areas. Dry sheets increased and deserts formed in Africa and Asia.

With global cooling, many cold-blooded animals disappeared from the middle and high latitudes. Crocodiles and alligators became extinct in Europe. Instead, birds and rodents evolved and continued to expand. And, when there is food, predators arise: the venomous snake genera multiplied in the Pliocene.

In Africa, animals with hooves abounded. The population of elephants increased and the first giraffes appeared. The proliferation of new predators, especially felines, motivated hyenas to become scavengers. Meanwhile, primates continued to evolve. Various species of hominids emerged, from the Australopithecines Homo habilis and Homo erectus, which are considered direct ancestors of Homo sapiens.

In Eurasia, tapirs, rhinos, antelopes and cows thrived. Some camel species arrived in Asia from North America. The first saber-toothed cats appeared, competing with other predators such as bears, dogs and weasels. North American species invaded South America, while in Australia, isolated from the rest, they continued to dominate the marsupials.

Discover more:
• The Messinian salt crisis
• Mastodons were very abundant in the Iberian Peninsula
• The Cenozoic era (part 2): The Neogenic Period (Video)

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The Paleogene: Paleocene, Eocene and OligoceneThe Quaternary: Pleistocene and Holocene