Neogene

A long time ago, the Earth changed. The land moved and made big mountains. North and South America even joined together. This changed how the warm ocean moved. The world began to get much colder. Many animals changed too. Birds and mammals grew into new forms. Grasslands grew where forests used to be. This helped animals like horses grow. The very first humans appeared in Africa. It was a time of big changes!

The Neogene was a long period of time. It lasted for 20.45 million years. During this time, the Earth changed in many ways. The continents moved to where they are today. For example, North and South America joined together. This happened at the Isthmus of Panama. This new land changed how ocean water moved. It cut off warm water from the Pacific Ocean. Because of this, the world grew much colder.

Animals also changed during the Neogene. Many birds and mammals grew into modern forms. Grasslands grew in places where forests used to be. This helped animals like horses and bison thrive. Large sharks lived in the oceans during this time. Near the end of this period, the first humans appeared in Africa. This group was called Homo habilis. The Neogene is divided into two parts. These are the Miocene and the Pliocene. Scientists study these parts to learn about our history.

The Neogene was a huge span of time in Earth's history. It lasted for 20.45 million years. This period is the second part of the Cenozoic Era. It began after the Paleogene Period ended. The Neogene is divided into two smaller parts called epochs. These are the Miocene and the Pliocene. Scientists study these times to understand our world. Many things changed during these millions of years. The Earth was moving toward the world we see today.

Much happened with the land and the water. The continents moved into positions very close to today. A major event was the Isthmus of Panama forming. This new land connected North and South America. It acted like a wall in the ocean. This wall blocked warm water from moving between oceans. This change helped the global climate grow much colder. Sea levels also fell during this long time. This created land bridges between different continents. These paths let animals move to new places.

The climate went through many different phases. The early Miocene was a relatively cool time. Later, the Middle Miocene Climatic Optimum brought warmth. This warm phase was driven by volcanic rocks. Around 11 million years ago, the world cooled again. Ice caps began to grow at the poles. Between 7 and 5.3 million years ago, it cooled more. This happened because carbon dioxide levels went down. During the Pliocene, there was another warm interval. This was called the Pliocene Warm Interval.

Life on Earth changed in amazing ways. Mammals and birds evolved into modern forms. Grasslands grew as the world became drier and cooler. This allowed animals like horses and bison to thrive. In the oceans, huge sharks called megalodons lived. About 19 million years ago, many shark species disappeared. The first humans, Homo habilis, appeared in Africa. They appeared near the very end of the period. Plants like daisies and grasses also became very common.

Scientists have spent a long time naming these eras. An Austrian scientist named Moritz Hörnes coined the term. He gave us the name Neogene in 1853. Geologists sometimes argue about where the Neogene ends. Some think it should include the Quaternary Period. Others say the Quaternary is a separate period. In 2009, a decision was made to settle this. The Neogene ends at 2.58 million years ago. This marks the start of the Quaternary Period.

The Neogene is a major geological period that shaped our modern world. It spans 20.45 million years of Earth's history. This period began when the Paleogene Period ended. It serves as the second period of the Cenozoic Era. The Neogene is also the eleventh period of the Phanerozoic Eon. Geologists use this time to study how our current continents and climates formed. Some scientists even debate where the Neogene ends and the Quaternary Period begins. This discussion exists because the most recent geological records are very detailed.

The Neogene is divided into two distinct epochs. The first is the Miocene epoch, which is the earlier part. The second is the Pliocene epoch, which is the later part. Within the Miocene, there are six specific ages. These are the Aquitanian, Burdigalian, Langhian, Serravallian, Tortonian, and Messinian ages. The Pliocene is divided into two ages: the Zanclean and the Piacenzian. These divisions help scientists organize the complex changes occurring in the Earth's crust and atmosphere.

Large-scale movements of the Earth's surface defined this era. The continents moved into positions very close to where they are today. One of the most significant events was the formation of the Isthmus of Panama. This land bridge connected North and South America late in the Pliocene. This connection acted as a barrier in the ocean. It cut off warm ocean currents from moving between the Pacific and Atlantic Oceans. This change left only the Gulf Stream to move heat toward the Arctic Ocean.

The climate during the Neogene underwent a long-term cooling trend. The early Miocene was relatively cool for the planet. However, the Middle Miocene Climatic Optimum (MMCO) brought a warm phase. This warmth was driven by the emplacement of the Columbia River Basalt Group. Around 11 million years ago, the world entered the much cooler Late Miocene. During this time, ice caps at both poles began to grow and thicken. This process was helped by the increased formation of sea ice.

Temperature shifts continued through the Pliocene epoch. Between 7 and 5.3 million years ago, the Late Miocene Cooling (LMC) occurred. This cooling was driven by a decrease in carbon dioxide concentrations. Later, the Pliocene Warm Interval (PWI) occurred from 5.3 to 2.7 million years ago. This interval had carbon dioxide levels similar to our current atmosphere. During the Pliocene, North Africa also experienced "Green Sahara" phases. These wet conditions occurred roughly every 21,000 years.

Life on land and in the sea changed significantly. Mammals and birds evolved into many modern forms. As the climate became drier and more seasonal, forests were replaced by grasslands. This allowed grazing animals like horses, antelope, and bison to thrive. In the oceans, massive predators like megalodons and livyatans dominated. About 19 million years ago, 70% of all pelagic shark species disappeared. Toward the end of the Pliocene, the first humans, Homo habilis, appeared in Africa.

History shows how we came to name this period. The term "Neogene" was coined in 1853 by Moritz Hörnes. He was an Austrian palaeontologist. Before this, many used the term "Tertiary Period." While "Tertiary" is no longer a formal term, it is still used informally. Geologists have worked hard to define the exact end of the Neogene. In 2009, the International Commission on Stratigraphy decided on a clear boundary. They set the end of the Neogene at 2.58 million years ago. This marks the beginning of the Quaternary Period.