We explain what the Cenozoic era is, how it is divided, its geology and climate. We also explain its characteristics, flora and fauna.
The Cenozoic is considered the “age of mammals.”
What is the Cenozoic era?
The Cenozoic era, or also the Cenozoic, is the last division of the geological time scale. It began after the extinction of the dinosaurs approximately 65 million years ago and continues to the present day.It is also known as the “age of mammals” because this was the preferred way of life throughout its entire existence. Furthermore, it is the era in which human beings made their appearance.
During the Cenozoic, The continents continued their drift from the supercontinent Pangaea to their present positionThis caused, among other phenomena, the formation of the largest mountain ranges today, oceans and seas, volcanoes and major plains.
On the other hand, the Cenozoic era was a stage in which The planet’s climate gradually cooled until it reached present levels.Ice ages were extended, and the drift of continents towards polar regions caused the formation of large ice blocks.
Name Cenozoic comes from Greek words kainos (“new and zoe (“form of life”, “animal”), so it means “new life”.
Features of the Cenozoic era
Some of the main characteristics of the Cenozoic era are:
- It began 65 million years ago and continues to the present day.
- It is subdivided into three periods: Paleogene, Neogene and Quaternary.
- During this era, the continents drifted to their present position.
- Mammals evolved and diversified.
- The first hominids appeared, which later evolved until the appearance of human beings.
- The climate was changeable, with moments of high temperatures and extensive ice ages.
Division of the Cenozoic era
The Quaternary period extends to the present day.
The Cenozoic era was divided into three periods, each subdivided into several eras:
- Paleogene periodIt began 65 million years ago and lasted until 23.8 million years ago. It is divided into three periods:
- Paleocene. It began 65 million years ago and ended 54.8 million years ago.
- Eocene. It began 54.8 million years ago and ended 33.7 million years ago.
- Oligocene. It began 33.7 million years ago and ended 23.8 million years ago.
- Neogene period. It began 23.8 million years ago and ended 1.8 million years ago. It is divided into two periods:
- Miocene. It began 23.8 million years ago and ended 5.3 million years ago.
- Pliocene. It began 5.3 million years ago and ended 1.8 million years ago.
- Quaternary periodIt began 1.8 million years ago and continues to the present day. It is divided into two periods:
- Pleistocene. It started 1.8 million years ago and ended 11,000 years ago.
- Holocene. It began 11,000 years ago and continues to the present day.
Disuse of the term Tertiary: At the beginning of the 20th century, the denominations were used Tertiary and Quaternary to name two major periods of the Cenozoic. However, the International Commission on Stratigraphy (ICS) decided to abandon the use of the term Tertiary in 2008. In its place, two new subdivisions were established to replace it: the Paleogene and the Neogene. On the other hand, the term Quaternary was preserved, then the subdivision of the Cenozoic era was established in Paleogene, Neogene and Quaternary.
Geology of the Cenozoic era
When the African plate collided with Eurasia, the Alpine orogeny occurred.
During the Cenozoic Era, the supercontinents Gondwana and Laurasia continued the separation that had begun in the Mesozoic, so that The continents were acquiring their current orientation and positionIn addition, the Atlantic Ocean widened, and North America and South America were joined with the creation of the Central American isthmus.
Another important geological event during the Cenozoic was the collision between the Indian and Eurasian plates 50 million years ago, which triggered the formation of the Himalayas, the highest mountain range on the planet. Furthermore, the African plate collided with the Eurasian plate 35 million years ago, which resulted in the definitive closure of the Tethys Sea and the formation of the Alps.
On the other hand, The Andes mountain range was also formedwhich extends from north to south in America, a product of subduction between the South American and North American plates with the Nazca and Pacific plates.
The last reliefs to form, and the newest in geological terms, were the plainsAs a consequence of the erosion of rocks and the transport of sediments by wind and rivers from higher areas to lower areas, large sedimentary basins were formed, such as the Amazon, the Indo-Ganges, the Mississippi and the Paraná, among many others.
Cenozoic Era Climate
The Cenozoic climate has been one of gradual cooling from the end of the Mesozoic era to the present day.. Although it is believed that this era ended after a sudden cooling due to solar blocking that produced ash in the atmosphere due to the K-Pg Event (which caused the extinction of the dinosaurs and many other forms of life), the Mesozoic had temperatures older than the Cenozoic era. This is because the succession of ice ages, added to the drift of the continents towards polar areas and the cooling of ocean water, decreased the global temperature of the planet.
However, Closer to our days, there were extended periods of atmospheric warmingThe Maximum Holocene was a period of time that began around 6000 BC and lasted until 2500 BC, during which temperatures rose considerably. The so-called “Medieval Warm Period” was also a time of rising global temperatures on the planet, between 700 and 1200 AD.
These warm and relatively stable stages lasting about 12,000 years until today were what allowed the expansion of human civilization on Earth during the Holocene.
Since the appearance of human beings, and especially in the last 200 years, the modification of the natural dynamics of the planet by societies was so accelerated that in recent years it was proposed to add a new geological era: the “ Anthropocene.” This new classification seeks to measure the enormous impact that the appearance of human beings has had in a very short geological time, especially on climate dynamics.
The ice ages
In interglacial periods, the heat increased and the ice retreated.
Some estimates indicate that during the Quaternary there were many periods of atmospheric cooling, which generated glacial periods or “ice ages.”
During the ice ages, the ice expanded, the seas sank, and the global climate cooled. In interglacial periods, however, the cold decreased, the ice receded and the level of the oceans increased.
In the last million years, four great glaciations would have occurred: the Günz glaciation (1.1 million years ago), the Mindel glaciation (580,000 years ago), the Riss glaciation (200,000 years ago) and the Würm glaciation (the most recent, 80,000 years ago).
Flora of the Cenozoic era
In the Cenozoic era, grasses and herbs emerged in the most arid areas.
In the Cenozoic era, vegetation expanded and diversifiedespecially during the early, warmer, wetter periods. Later, the forests began to give way to drier, more arid areas that formed in the interior of the continents. This is how grasses and herbs emerged.
After the appearance of human beings, and especially after the Neolithic revolution, edible and cultivable species began to predominate. and to develop in many parts of the world thanks to the practice of agriculture.
Continental separation also allowed greater diversification, in addition to the appearance and evolution of endemic species, which are those that are only found in specific places on the planet and that did not diversify territorially.
Fauna of the Cenozoic era
Mammals proliferated during the Cenozoic era.
At the beginning of the Cenozoic era, The surviving species of the Cretaceous-Paleogene mass extinction were mostly small mammals, reptiles and birds.. That is why they were the ones that proliferated the fastest, stripped of their large predators.
Among the mammals, there were rodents and small equines. Their biggest predators became large flightless birds, such as those belonging to the genus Titanis.
In the Neogene, the first primates appeared, and among them the first hominins, ancestors of the human race.In addition, cattle, antelopes, gazelles and other large mammals flourished during this period, as did aquatic mammals such as whales.
Finally, the Quaternary was characterized by the presence of large feline predators, such as saber-toothed tigers. Woolly mammoths, adapted to ice ages, also proliferated.
The presence of humans influenced the fate of many of these species. Some of them became extinct due to increased hunting by this new species, which little by little became the dominant one on the entire planet.
Evolution of humanity
He Homo sapiens It is the only species not extinct today.
In the Quaternary period, the first human beings appearthe product of a slow process of evolutionary changes starting with the first hominids that emerged on the African continent.
When these hominins migrated to Eurasia and the Middle East, they gave rise to new human species. The last ones were the Homo neanderthalensis (Neanderthal man), the Homo denisovensis (Denisova hominid) and the Homo sapiensthe only species that survived to the present day and which we commonly refer to as “human beings”.
References
- AstroMía. (sf). The Neogene. Miocene and Pliocene. https://www.astromia.com/
- EcuRed. (sf). Cenozoic Era. https://www.ecured.cu/
- Gullo, J., Nardulli, JP, Echeverría, MJ, Capuz, SM, Lazzaro, Y. (2020). The hominization process. In Social Sciences. Societies and environments of the world. From the first societies to the end of the Middle Ages (pp. 139-152). AZ. http://az.com.ar/
- Milo, A. (2023). Anthropocene, the geological era defined by human impact on Earth. National Geographic in Spanish. https://www.ngenespanol.com/
- Tarbuck, E. & Lutgens, F. (2005). Earth sciences. An Introduction to Physical Geology. Pearson Education.