Cretaceous

Cretaceous

Definition:

The Cretaceous or Cretaceous describes an epoch of geology that began 145 million years ago and lasted about 80 million years. The name derives from the Latin word "Cretaceum" and refers to rock formations and fossils of sea-dwelling crustaceans that are predominantly made of limestone and come from the cretaceous. The term was coined by the Belgian scientist Jean Baptiste Julien d 'Omalius d'Halloy in 1822. The cretaceous is today divided by scientists in the Lower and Upper Cretaceous, with each series are assigned six levels.

Climate:

The climate in the Cretaceous was characterized in comparison to the previous age of slightly cooler temperatures, but still mild and relatively high humidity. Even in the Cretaceous, the polar ice caps were completely ice-free and the sea level compared to today significantly higher, which led to large-scale flooding on the continents. Also indications of icing on the land masses are missing completely. Worldwide vegetation suggests that in the Cretaceous there were no significant differences in temperatures between the equatorial regions and those of the poles. The researchers found, however, that in particular in the upper Cretaceous dominated in places cooler temperatures, which resulted in a lower content of carbonic acid in seawater and led to a reduced formation of limestone.

Geology:

In the Cretaceous, shallow seas covered large areas of the continents, especially North America and Europe. Central Europe was almost completely submerged, which is why extensive deposits of limestone, the so-called cretaceous, are found in this region today. Tectonic plates collided during this period, bringing with them the formation of the Alps, the Himalayas, the Rocky Mountains and the Andes. The two large continents Laurasia and Gondwana, which in turn were decaying, drifted farther and farther apart, until the distribution of the land masses towards the end of the Cretaceous took about the outlines and geographical arrangement that exist today.

Flora and Fauna (plants and animals):

The development of the flora took a big step in the Cretaceous, because now more and more overgrown plants such as magnolias, poplars, willows and the forerunners of today's lilies appeared. The deciduous trees gradually colonized all continents and spread more and more. The cretaceous is also significant because of the appearance of the first grasses. In particular, weeds, sweet grasses and weed grasses, as well as grasses that can be found today on every meadow, developed rapidly in the Cretaceous from the first monocotyledonous plants. Due to the increased growth of grasses, the soil structures changed in favor of a solid, well-rooted subsoil. The soils could be much better aerated and thus offered better living conditions to animals that lived in them, which also benefited the fertility of the earth.

From the cretaceous come fossils, which indicates a rapid development of reptiles with only one pair of legs to today's snakes. In fact, the first snakes appeared until the end of the Upper Cretaceous, probably descended from monitor lizards and similar lizards. In addition to the Archeopteryx, which still had teeth in its beak, appeared in the cretaceous, the first species without pine, which can already be counted among the class of today's birds and could fly or walk. While the giant dinosaurs gradually died out in the course of the Cretaceous and in the Upper Cretaceous, only a few herbivorous species populated the earth, the group of mammals, which no longer consisted of insectivorous species, was on the rise.

Summary

The Cretaceous or Cretaceous is a section of the earth's history, which lasted from about 145 million years ago to 66 million years ago.

The Cretaceous owes its name to the found, calcareous (calcium carbonate) fossils of that time.

The impact of a meteorite on the Yucatan peninsula at the end of the Cretaceous period probably led to the extinction of the dinosaurs. However, a longer-lasting phase of increased volcanism during the Cretaceous is also considered as the cause.