During the Cenozoic era there were various changes on the planet both in terms of geology and flora and fauna. Today we are going to talk about the third epoch that made up the Cenozoic. Its about Oligocene. The Oligocene spanned from about 33.9 million years ago to about 23 million years ago. In all these years our planet underwent notable changes. These changes are what caused a redistribution of living beings, both plants and animals. In addition, the climate played a fundamental role during the process of changes in living beings since it created some conditions so that certain animals or plants could prosper more and others could not survive. In this way, a new form of natural selection was established.
In this article we are going to tell you everything you need to know about the Oligocene.
Key features
The Oligocene is an era that has always fascinated all specialists who focus on studying the geological time. All those who have spent enough time to be able to know the hidden aspects of the different geological stages of the planet have been left with the fascinating things that happened to our planet during the Oligocene.
This is a time that has lasted an average of 11 million yearsDuring this period, the continents were reorganized thanks to the movement of the continental plates. This movement caused the continents to occupy positions similar to those they occupy today. The Oligocene is also known as the Age of Mammals. This is the group of animals that experienced the greatest diversification and variety during this period. It is during this 11-million-year period that subdivisions of mammals, such as rodents and canids, appear.
Regarding the geology of the Oligocene, it was a time of considerable geological and orogenic activity. We can see that the fragmentation of the super continent Pangea continued and many of its fragments were displaced to occupy a position similar to the ones they have today. Two large-scale orogenic processes took place during this time: the Laramide Orogeny and the Alpine Orogeny.
Oligocene Geology
We are going to go through all the characteristics of the Oligocene one by one. We start with geology. The fragmentation of the super continent known as Pangea it became more and more evident when the fragment that corresponds to South America was separated. This displacement of the continent caused a slow movement towards the west in order to meet North America and form what we know today as the American continent in its entirety.
Antarctica continued to separate from the rest of the continents, deepening its ice cover as it drew ever closer to the South Pole. Many specialists have disputed various conclusions, such as that at this time the African plate collided with Eurasia and also with the fragment we now know as India. It is interesting to note how, by the end of the Oligocene, all land masses were already in a position quite similar to that in which we find them today. The same is true of the oceans, where the oceans were arranged in such a way that there were several oceans separating the present-day continents. Among these oceans we can mention the Pacific Ocean, the Atlantic Ocean and the Indian.
Oligocene climate
As for the Oligocene climate, the conditions were quite extreme. It was characterized mainly by very low temperatures. Throughout this period, both Antarctica and Greenland remained covered in ice, and the ice continued to expand. Furthermore, when Antarctica completely separated from South America, it caused various ocean currents to circulate around it. One of these ocean currents is the Antarctic Circumpolar Current. This ocean current is considered one of the most important, as it was responsible for the ice covering of the entire continent of Antarctica and the formation of glaciers.
The decrease in global temperature caused consequences in the modification of some ecosystems. The predominance of vegetation was coniferous and deciduous forests. These trees have been able to survive these extreme environments because they are well-suited to surviving in low temperatures. You can learn more about the fauna associated with this period in the article on Paleogene fauna.
Flora and fauna
Life became increasingly diverse, both in plants and animals. Despite the unfavorable climatic conditions, organisms were able to adapt to them and survive.
Let's talk about the flora first. The Oligocene flora is characterized by the fact that angiosperms could begin to spread through a large number of habitats. These plants even reached the dominance they enjoy today. Throughout this period, tropical forests declined due to the drop in global temperatures. These tropical forests were replaced by herbaceous plants and grasslands that were adapted to more extreme temperatures. These grasslands and herbaceous plants spread across all continents. These plants' adaptation was due to their continuous growth rate, which allowed them to survive harsh weather conditions.
Herbaceous plants enjoyed great evolutionary success thanks to the adaptation of their own growth characteristics. These plants have a continuous growth rate that never stops. Furthermore, these types of plants had to deal with the action of various animals, such as the grazers that fed on them. This is how they were able to develop different adaptive capacities to survive in these environments and even establish a symbiotic relationship with other animals, as can also be observed in the flora of the Oligocene. During this period, Legume-type plants such as beans were developed.
Regarding fauna, many animal groups were able to diversify and expand their range. Despite the climatic conditions in which they found themselves, many animal groups, such as birds, reptiles, and mammals, expanded their range.
There were birds and reptiles, although the greatest notoriety was taken by mammals. Importantly, the Cenozoic is considered the era of mammals.
I hope that with this information you can learn more about the Oligocene.