May 28, 2022

The Eocene (55.8 Ma - 33.9 Ma before the present) is a geological epoch belonging to the geological era of the Cenozoic, to its oldest period of the Paleogene, resp. informal geological units of the Tertiary. He derived the name of the Eocene from the ancient Greek word "ἠώς" (éós), which means dawn, and also the Greek word "καινός" (kainos) - Latinized to "caenus", meaning new. The name, which can be translated as "dawn of new times", indicates that according to fossil finds, it was during this period that a number of surviving groups of animals were born.

Geology and climate

At the interface of the Paleocene and Eocene, the world went through a stage of extreme warming (the so-called thermal maximum). The distribution of continents at this time was close to the present. At the South Pole was already Antarctica, from which Australia was moving away and north, and South America was moving away from it. At the end of the Eocene, at the turn of the later Oligocene period, Australia broke away completely. Africa was approaching Europe and Asia, causing the closure of the tropical ocean of Tethys, leaving the Mediterranean and Caspian and Aral Sea to this day. The approach of these tectonic plates caused further phases of the Alpine fold, which took place from the Mesozoic. The Indian subcontinent also traveled to the north, but in the older Eocene it was only a large island in the ocean. migration of animals, yet in the Lower and Middle Eocene there were transitions both between Asia and Europe and Europe and North America. The Atlantic Ocean was expanding, but the two Americas, which were separated by the sea, were moving away from Europe and Africa. The climate in the Lower Eocene was marked by significant warming. Tropical rainforests spread far to the north and south, behind which stretched a zone of paratropic forests, ie thermophilic forests with a dry and rainy season, similar to those found today in Mexico, for example. As far as the polar regions, non-deciduous subtropical forests intervened, and there were special deciduous deciduous forests in the polar regions themselves. The trees in these forests were adapted to the cycle of polar days and nights, when for long periods of darkness in the winter the leaves fell off the trees, just as trees in the temperate zone do today, but they do so due to the cold. A similar habitat is completely unimaginable in today's world. From the Middle Eocene, temperatures began to gradually decrease and with them the climate also dried up. At that time, Australia separated from Antarctica, which was surrounded by circumpolar sea currents, which isolated the continent from the rest of the world and it began to cool. It was in the latest Eocene that a glacier shield began to form on it. In the northern hemisphere, a strait opened into the Arctic Ocean, allowing contact with its cold waters in the Atlantic. Together with other possible global influences, such as fluctuations in the carbon dioxide content of the atmosphere, these events have caused a global cooling. The result was a redrawing of habitat maps around the globe. Tropical rainforests have receded near the equator, and in the warmer and warmer regions of Antarctica, a new habitat of mixed coniferous and deciduous deciduous forests, as we know it today, has spread. Due to the cooling, the sea level also dropped, revealing new lands and creating some important migration routes for the fauna.


The climate throughout the Eocene period was significantly warmer than today. The warmest was in the lower eo