Miocene

A long time ago, the Earth changed.

The world slowly grew cooler. This cooling led to ice ages. Grass grew in many places. Forests became smaller.

New plants grew in the sea, too. Long seaweed forests appeared in the water. Apes also lived during this time. Some ancestors of humans lived then. They began to follow their own path. It was a time of big changes for our world.

The Miocene was a long time in Earth's history.

It began about 23 million years ago. During this time, the world slowly grew cooler. This cooling led toward future ice ages. As the world cooled, grasslands grew larger. Forests became much smaller.

Many animals we know today lived then. Mammals and birds were well established. In the ocean, kelp forests appeared. Kelp is a type of large seaweed. These forests became very important for sea life.

Land and seas changed in big ways. Africa and Arabia crashed into Eurasia. This made a land bridge. Animals could now move between continents. Apes also began to spread across the Old World. Even the ancestors of humans began to follow their own path. In the sea, the Mediterranean almost dried up. This was called the Messinian salinity crisis. Later, water rushed back in through the Strait of Gibraltar. This was called the Zanclean flood.

These big changes helped shape our modern world.

The Miocene was a huge part of Earth's history.

It was the first epoch of the Neogene Period. This time began about 23 million years ago. It lasted until about 5.3 million years ago. The name comes from Greek words meaning "less recent."

This is because it had fewer modern sea creatures than the period that followed. During this time, the world began to change. The climate slowly cooled down. This cooling led toward a series of ice ages. This shift changed how life lived on the planet.

Many things happened as the Earth changed. First, the climate began a long cooling trend. As it cooled, grasslands grew larger across the land. At the same time, forests began to dwindle. In the oceans, a new thing happened. Kelp forests made their first appearance. These forests became a very productive home for sea life.

Mammals and birds were already well established. Whales and other sea animals also spread through the water. The plants and animals looked much like the ones we see today.

Geologists have studied how the land moved. The Indian Plate crashed into the Eurasian Plate. This collision created huge mountain ranges. It also lifted the Tibetan Plateau high into the sky. In Africa, a piece called Afro-Arabia collided with Eurasia. This created a land bridge between the continents.

This path let animals move between different lands. It allowed apes to spread across the Old World. Even the ancestors of humans began to follow their own path. This happened during the final stages of the Miocene.

There were many big events in the seas. One major event happened in the Mediterranean Sea. The connections to the Atlantic Ocean closed up. This caused the sea to almost completely dry up. Scientists call this the Messinian salinity crisis.

Later, the Strait of Gibraltar opened up. This allowed water to rush back in. This event is known as the Zanclean flood. These changes moved huge amounts of water and salt around the world.

We can see how the Miocene shaped our world. The continents drifted toward the spots they hold now. In South America, the Andes mountains began to rise. This mountain growth created a dry area called the Patagonian Desert. In Asia, the new mountains changed the wind and rain patterns.

Many of these changes link to the world we know. The cooling of the Earth and the movement of land set the stage for modern life. The Miocene was a time of great building and moving.

The Miocene is the first geological epoch of the Neogene Period. It began approximately 23 million years ago and lasted until about 5.3 million years ago.

The name was chosen by the Scottish geologist Charles Lyell. He used Ancient Greek words to create a name meaning "less recent." This describes the fact that the Miocene has 18% fewer modern marine invertebrates than the Pliocene epoch. This epoch is a vital period for scientists studying Earth's history. It helps them understand how our modern climate and life forms developed.

During the Miocene, the Earth's climate underwent a slow cooling process. This cooling trend moved the planet toward a series of ice ages. One significant warm period occurred during the Middle Miocene Climatic Optimum, or MMCO. This interval began about 16 million years ago. During the MMCO, carbon dioxide levels were between 300 and 500 ppm. The global annual mean surface temperature reached about 18.4 °C. This warmth was driven by the activity of the Columbia River Basalts. It was also enhanced by a decrease in albedo, which is the reflection of sunlight. This happened because deserts shrank and forests expanded.

The physical landscape of the world changed through massive tectonic movements. In Asia, the Indian Plate continued to collide with the Eurasian Plate. This collision created new mountain ranges and lifted the Tibetan Plateau. This uplift changed monsoonal patterns in Asia. These patterns were linked to glacial periods in the northern hemisphere. In the early Miocene, the Afro-Arabia landmass collided with Eurasia. This collision severed the connection between the Mediterranean and Indian Oceans. This event allowed different animals to move between continents. It enabled the dispersal of proboscideans and hominoids into Eurasia.

Evolutionary changes were also widespread during this epoch. In the early Miocene, specifically during the Aquitanian and Burdigalian stages, apes first evolved. They began to diversify and spread throughout the Old World. By the end of the Miocene, the ancestors of humans had split from the ancestors of chimpanzees. This split happened during the final Messinian Stage, between 7.5 and 5.3 million years ago. On land, grasslands continued to expand while forests began to dwindle. In the oceans, kelp forests made their first appearance. These became one of the most productive ecosystems on Earth.

The Mediterranean Sea experienced dramatic changes during the late Miocene. The connections between the Atlantic and the Mediterranean closed. This caused the sea to almost completely evaporate. Geologists call this event the Messinian salinity crisis.

Later, at the Miocene–Pliocene boundary, the Strait of Gibraltar opened. This caused the Zanclean flood, where the Mediterranean refilled with water. In South America, the Antarctic Plate began to subduct beneath the continent 14 million years ago. This created the Chile Triple Junction. As the southern Andes rose during the Middle Miocene, they created a rain shadow. This process led to the formation of the Patagonian Desert.

Scientists divide the Miocene into several distinct faunal stages. These stages are named by the International Commission on Stratigraphy. The youngest stage is the Messinian, which lasted from 7.246 to 5.333 million years ago. Before that was the Tortonian stage, from 11.63 to 7.246 million years ago. The Middle Miocene includes the Serravallian and Langhian stages. The Early Miocene is composed of the Burdigalian and Aquitanian stages.

Different regional systems also exist. These systems are based on characteristic land mammals found in Europe, North America, and South America. These names help researchers track how life changed in specific parts of the world.

The Miocene is essential for understanding modern environmental systems. The movement of continents and the cooling of the climate shaped today's oceans and land. The expansion of grasslands and the rise of mammals and birds set the stage for modern biology. Even the way water moves through the oceans was changed. For example, the opening of the Fram Strait allowed Atlantic water to flow into the Arctic Ocean. This connection lasted until the Quaternary period. By studying the Miocene, scientists can better predict how our current climate might change in the future.