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Oligocene Epoch

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The Oligocene period is the geologic epoch related to the Paleogene period this extends from about 33.9 million to 23 million years. Like other older geologic periods, the rocks which define the epoch are truly identified but these exact dates of the start and end of the epoch are a little uncertain. 

The name Oligocene originated in the year 1854 by a palaeontology must have named Heinrich Ernst Beyrich. His name comes from the Ancient which refers to the extant forms of mollusks. This period is preceded by Eocene Epoch which is then followed by the Miocene Epoch. While Oligocene is the third and also final epoch of the Paleogene Period.

Oligocene Period 

Oligocene Period is the third and last major worldwide division of the Paleogene Period which is 65.5 million to about 23 million years ago. This is the interval between 33.9 million to 23 million years ago. The Oligocene Epoch is here subdivided into two ages, we present their corresponding rock stages as well:

The Rupelian Age

The Chattian Age. 

This is being followed by the Eocene Epoch and was succeeded by the Miocene Epoch, while the first epoch was the Neogene period. The term used ‘Oligocene’ is being derived from Greek which actually means the “epoch of the few recent forms,” this is being referred to as the sparseness of the number of these modern animals which originated during that time.

In the western part of Europe, the beginning of the Oligocene period was marked by the invasion of the sea which was brought with it by the new mollusks which is a prominent characteristic of the epoch. The marine conditions did not exist in this period for long, however, the brackish and freshwater conditions soon prevailed during this time.

Oligocene Animals 

The earliest forms of amphicyonids, canids, tayassuidae, camels, protoceratops, and the anthracotheres showed in this time. Birds like Caprimulgiformes who have gaping mouths to catch the insects also appeared in this period. Diurnal raptors like the falcons, hawks, and eagles with seven to ten families of rodents also originated during the Oligocene Period.

Aluvarus praeimperialis is a type of bony fish, which is extinct, they are known from headless fossil specimens that are found in the Elam Formation.  

Oligocene Climate

Oligocene cherished a climate that appeared to have been of a temperate type, there were many regions that enjoyed the subtropical climatic conditions in this region. The grasslands also expanded and the forested regions dwindled in this time. Here the tropical vegetation flourished along the borders of the Sea named Tethyan. Then existed warm, swampy conditions. This specific type of condition prevailed over much of Germany and had extensive deposits of lignite coal.

Oligocene Epoch Animals 

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Another prominent group of Oligocene was the marine organisms – foraminiferans, protists. This group was quite similar to amoebas but they bore a complex, and a general calcareous test, or the shell. The prominent foraminiferans were known as the nummulites which were large, lens-shaped foraminiferans. The other marine form is essentially quite modern in approach.  

The terrestrial consists of the invertebrate life where abundant and diverse vegetation grew. The deposits of the lake and stream on the Isle of Wight in England also contain the remains, often well preserved. The Baltic and many other forms of Oligocene insects that includes butterflies, bees, ants, and spiders live here in amber.  

Oligocene Fossils 

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The climatic change occurred approximately 34 million years ago in Africa and not in Asia. More specifically said, the climate marking of the Eocene-Oligocene Transition (this occurred about 34 million years ago) which could have acted as an evolution filter, this allows different types of primates to evolve in the land of Africa while compared to Asia. The ensuing dominance of the subset of primates was known as anthropoids which were located in the African regions, this must-have led to the evolution of humans in this part according to a paper in Science. Even though the early fossils were found in Asia, the actual evolutions of human beings occurred in Africa. 

Oligocene Mammals

The Oligocene period marked the advent of large gigantic mammals. Rhinoceroses also reached great heights similar to the animal called Paraceratherium. Dogs and cats were land carnivores animals while dogs and cats were the primary land carnivores and the whales were carnivores at sea. The mammals during the Oligocene period were “Micro-mammals" who experienced a period of diversification. This period was also characterized by free change of animals among the northern continents, as this was seen by the similarity of invertebrate faunas.

Oligocene Plants

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Grasses were the plants that first grew near the water margins in the Eocene after which they became more common in the open habitats. In Northern America the flora also consisted of a mixture of subtropical elements, among others popular were - cashews and lychee trees, also there thrived temperate trees as well such as roses, beech, and pine.Oligocene Epoch Animals

FAQ (Frequently Asked Questions)

1. How Long Did Oligocene Epoch Last?

Ans. The Oligocene epoch was a part of the Tertiary Period in the Cenozoic Era, this lasted from about approximately 33.7 to 23.8 million years ago. The Oligocene is only a relatively short span of time, here a number of major changes occurred during this time. 

Oligocene Epoch was the third and last worldwide division of the Paleogene Period (which was 65.5 million to 23 million years ago) the interval was between 33.9 million to 23 million years ago. The Oligocene Epoch is again divided into two ages with their corresponding rock stages - the Rupelian and the Chattian.

2. What Do You Mean By Invertebrate Life?

Ans. An invertebrate is defined as a class of animal species that do not have their backbone, like spiders, insects, mollusks, crabs, and lobsters. This is an estimation that more or less 97% of all animal species are invertebrates.

Terrestrial Invertebrate evolved in the Oligocene Epoch period.  

3. Why Did Oligocene Epoch End?

Ans. There were other factors that led to the decline of this period, the most dominating were the climate changes and the competition with today's modern cetaceans and the requiem sharks which existed in the Oligocene period as well. 

Thus the period lasted for a shorter span of time, while major changes were evident during this time.