The Tertiary period is an outdated name for the time interval of the geological history of the Earth, covering the period from the Cretaceous-Paleogene extinction (including the extinction of dinosaurs) (about 65 million years ago) to the beginning of the last ice age (about 1.8 million years ago). It was considered one of the two geological periods of the Cenozoic era .
The term was proposed in 1759 by the Italian geologist Giovanni Arduino , who, based on the geology of northern Italy, broke the time scale into primary , secondary and tertiary periods. A little later the Quaternary period was added to them. In 1828, the Scottish geologist Charles Lyell included the tertiary period in his more elaborate classification system. He divided the tertiary period into four epochs , based on the percentage of stratum of fossil mollusks close to modern species. For ages, Lyell used the Greek names: Eocene , Miocene , Ancient Pliocene and New Pliocene . Although this division was adequate for the region that the scientist studied (part of the Alps and plains of Italy), when trying to apply it to other parts of Europe and America, it turned out to be unsuitable, and therefore the use of fossil mollusks in the definition of eras ceased, and the eras themselves were renamed and redefined.
At the end of the Tertiary period, the first monkey-humans appeared on Earth  .
According to the current geochronological scale , the period of time previously known as the “Tertiary period” covers the Paleogene , Neogene, and part of the anthropogen .
The Paleogene (from 66.0 to 23.03 million years ago  ) was marked by the widespread and greatly increased diversity of mammals that evolved to occupy places freed by dinosaurs . The end of the period is associated with the drainage of the climate and the gradual warming of land. Includes the Paleocene , Eocene and Oligocene .
Neogene (from 23.03 to 2.588 million years ago  ) - in contrast to the Paleogene, the period of specialization of mammals: the number of their species decreases, and the relationship between them becomes closer. The climate is becoming more and more dry, and the average temperature drops until 1.8 million years ago, dry and cold ice ages begin. Includes the Miocene and Pliocene .
- Cenozoic era
- International Stratigraphic Scale (August 2012 version) on the website of the International Commission on Stratigraphy
- Andrusov N.I. ,. Tertiary system // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.