Ordovician period of the Paleozoic era: flora and fauna

The Ordovician period (system) is the second layer of deposits of the Paleozoic group in the history of the geology of our planet. The name came from an ancient tribe of Ordovics. They lived in Wales, Britain. This period was recognized as an independent system. It existed five hundred million years ago and lasted sixty million years. The period is allocated on most of the modern islands and on all continents.

Geology of the Ordovician system

At the beginning of the period, North and South America were close to Europe and Africa. Australia was close to Africa and was part of Asia. One of the poles was in the northern part of Africa, the other - in the northern part of the Pacific Ocean. At the very beginning of the Ordovician, the mainland of Gondwana occupied the greater part of the south of the earth. It included the present South America, the south of the Atlantic Ocean, Australia, Africa, the north of Asia and the Indian Ocean. Gradually, Europe and North America (Laurentia) began to move away from each other. Sea level was rising. The greatest part of the land was in warm latitudes. In Gondwana there were mountainous and later continental glaciers. In South America and in north-western Africa, sediments of the bottom moraines have been preserved, which the Paleozoic era left behind .

The Ordovician period in the Arabian Peninsula, in the south of France, Spain is characterized by icing. Traces of ice are also found in Brazil and not in the west of the Sahara. The expansion of marine areas occurred in the middle of the Ordovician period. In the western part of the North and South America, Britain, in the Urals-Mongolian belt, in the southeast of Australia, the traces of Ordovician deposits reach up to ten thousand meters. In these places there were many volcanoes, accumulated lava. Also found are siliceous rocks: jasper, phtanide. On the territory of Russia, the Ordovician period is clearly visible on the East European, Siberian platforms, the Urals, Novaya Zemlya, the Novosibirsk Islands, the Taimyr Peninsula, Kazakhstan and Central Asia.

The climatic situation in the Ordovician system

In the Ordovician period, the climate was divided into four types: tropical, temperate, subtropical, nival. In the late Ordovician cold weather occurred. In tropical regions, the temperature dropped by five degrees, in the subtropical regions by fifteen. It was very cold in the high latitudes. In the Middle Ordovician, a warmer climate was observed, compared with the previous era. This proves the spread of limestone rocks.

Mineral resources in the Ordovician system

Among the fossils formed in this period are oil and gas. Especially many deposits of this period in North America. There are also deposits of oil shale, phosphorite. These deposits are explained by geological processes, in which magma was involved. For example, in Kazakhstan there are deposits of manganese ores, as well as barite.

Seas in the Ordovician period

In the middle Ordovician, there is an expansion of marine areas. The bottom of the seas becomes lower. These changes strongly influenced the accumulation of a large layer of sedimentary rocks, which are represented by black mud. It consists of the ashes of volcanoes, clastic rocks and sand. On the territory of modern North America and Europe, there were small seas.

Vegetation world of Ordovician and fauna

Algae in the Ordovician period did not change when compared with the previous period. The very first plants on earth appear. Basically they are represented by mosses.

Life in the water in this period is quite diverse. That is why it is considered very important in the history of the Earth. The main species of sea creatures were formed. The first fish appear. Only they are very small, about five centimeters. The sea creatures began to appear hard cover. This happened because living organisms began to rise above the bottom sediments and feed above the seabed. More and more there are animals that feed on sea water. Some groups of vertebrates have already evolved, others have only just begun to develop. At the end of the Ordovician, vertebrate organisms appear. From the echinoderms, there appeared marine bubbles, sea lilies. At present, such organisms as sea lilies and starfish also exist.

Over the sea lilies a flock of jellyfish swims - this is a beautiful picture from ancient times. Owners of shells also begin their life. The gastropods and lamelliformes are represented by a large number of species. Ordovician develops four-branch cephalopods - these are primitive representatives of nautiloids. These organisms still live in the depths of the Indian Ocean. The shells of the ancient representatives of these living beings were straight, unlike the bent shells of the modern nautilus species. These mollusks led the life of a predator.

New animals during this period were graptolites. They multiplied by budding. The graptolites created colonies. Earlier they were referred to coelenterates, now - to the frog invertebrate animals. At the moment, the graptolites do not live, but there are their distant relatives. One of them lives in the North Sea - this is Rhabdopleura normanni. There is also a group of organisms that helps corals build reefs. They also appeared at this time - these are bryozoans. They exist even now, these organisms look like beautiful lace bushes. These were the aromorphoses of the Ordovician period in living organisms.

Inhabitants of the seas

In the sandstones in the state of Colorado fragments of unmixed fish were found. Extracted and other remains of vertebrate beings, similar to a shark. Fossils show that the swarthy Ordovician is different from today's species.

The first animals, which had teeth, are conodonts. These creatures are like eels. Their jaws are different from the jaws of living beings. Scientists counted six hundred species of living creatures that lived in the seas in the above-described period. Cooling has become one of the reasons for the extinction of many species. The shallow seas turned into plains, and the animals of these seas died. The same result has comprehended the plant world of this period.

Cause of extinction of animal organisms

There are many versions of mass extinction of creatures:

1. A burst of gamma rays within the solar system.
2. The fall of large bodies from space. Their fragments or meteorites are still found today.
3. The result of the formation of mountain systems. Under the influence of wind, the rocks are weathered and fall into the soil. As a result of these processes, little carbon remains, which affects warming.
4. Moving Gondwana to the South Pole led to a cold snap, and then to glaciation, a decrease in the water level in the World Ocean.
5. Saturation of the world ocean with metals. The investigated plankton of that period contains an elevated level of the most diverse metals. There was a poisoning of water by metals.

Which of these versions seems to be reliable, and why the animals of the Ordovician period have died out, is for the time being for certain unknown.