Silurian

Silurian

The Silurian Period

Definition:

The Silurian describes a temporal part of Earth's history, which began about 443 million years ago and lasted about 28 million years. The name of this geological era is due to the Scottish geologist Roderick Murchison, who coined it in 1833. He named the Silurus after a Celtic tribe that once inhabited Wales and western England, as in this part of Britain for the first time sedimentary rocks from this era were uncovered and then scientifically studied. The researchers today divide the Silurian into several series and stages, all bearing names borrowed from English and Welsh.

Climate:

The climate of the Silurs was characterized by mostly mild to warm temperatures, only on the South Pole it was probably seasonally dependent in a few months to temporary icing. While the mainland, as in the Ordovician, was characterized almost exclusively by dry desert zones, the climatically induced high water level led to the formation of tropical shallow seas, which led to widespread flooding. These are indicated by salt deposits on the continents of the northern hemisphere, such as today's Siberia and North America.

Geology:

The arrangement of the land masses was very similar to that of the previous Ordovician. The continents that are today in the northern hemisphere had already migrated in the Silurian to the regions north of the equator, the North Pole was in the Pacific. Large-scale lime deposits in Portugal and Spain, in the Alps and in large parts of North Africa suggest that a large part of southern and central Europe was also covered in Silur by island-rich shallow seas. The mountainous regions of today's Scotland, Sweden and Norway originated in the Silurian, after the Ur-Northern Europe collapsed with Laurentia and deposits in the Caledonian Sea were unfolded. Made up of Ur-Northern Europe and Laurentia, Eurasia became a major continent, retaining its shape and size for almost three hundred million years. In large parts of Europe, including Wales, Spain and Germany, graptolith shales in offshore regions indicate deposits from the Silurian. Red weathered shales and Silurian sandstones are now widely used in England and Scandinavia.

Flora and Fauna (plants and animals):

The Silurian is mainly due to the occurrence of vertebrates with pine-like structures in the mouth, which probably focused on life in fresh water. Among the echinoderms, the development of the so-called bud radiator, the precursor of the hair stars and sea lilies is worth mentioning. The wildlife was still mainly dominated by marine snails and shells, but also giant scorpions, which reached lengths of almost two meters, and bony fish appeared in Silur in an extraordinary variety. Gradually scorpions and millipedes conquered the mainland as well. The Silur also brought a milestone in the development of the flora with it, as it now appeared the Urfarne as the first vascular plants and simple Bärlapppflanzen. These plants had on the surface stomata, which served for the exchange of gases. Propagation of these early plants took place exclusively through the spread of spores. The first symbiotic connections between green plants and fungi in the form of lichens have also been detected from the Silurian.

Summary

The Silur (formerly Gotlandium) is a section of the Earth's history that lasted from about 443 million years ago to 419 million years ago.

The term Silurus derives from a Celtic tribe, the Silurians. The name was chosen by Scottish geologist Roderick Murchison.

In the course of the Silurian, bony fish appeared in the oceans and oceans for the first time. In contrast, lichen (symbiosis of alga and fungus) conquered the mainland for the first time.