LITMIR.BIZ

      In the Cambrian organisms, first of all, learn to build strong skeletons, according to which they are detected by paleontologists. The star of this period is trilobite, a pretty pretty arthropod, a prototype of modern cancer. There are also those that, with some stretch, can be classified as cephalopods – reminiscent of octopuses and squid. Their flowering falls on the Ordovician. The Silurian, which lasts «only» 25 million years, is marked by two mass extinctions (up to 50% of the marine life). One of them, which occurred 443 million years ago, the so-called. Ordovician-Silurian is probably due to the movement of Gondwana to the South Pole, as well as a sharp drop in the ocean level. Especially got, already was prosperous brachiopods (something like oysters), bivalve molluscs, bryozoans (colonies of small worms) and corals. The Devonian period is characterized by terrestrial vertebrates, famous brush-trotter fish, insects, as well as gymnosperms («bare» seeds hide in cones), fern-like and horsetail. Racoscorpions and fish appear. Trilobites, on the contrary, with such an abundance of predators, are rapidly dying out. However, the massive sea at the end of the Devonian, affects more than half of the entire marine life and flora; the reason for this, perhaps – the notorious comet.

      A fairly long (60 million years) Carboniferous period, or carbon begins 359 million years ago, it is characterized, as the name implies, by intense coal formation. The gymnosperms are developing and thriving: coniferous, cordaite (trees resembling these very conifers), and cicadassia (a cross between palm and fern), mussels and horsetails. In warm bogs amphibians prosper (stegocephalus, they are labyrinthodontes resembling crocodile-newt), ripidity (even larger, 8-meter crocodile), in the seas – sharks reaching 13 meters in length. In the air hover mega-moves – dragonflies with a wingspan of up to 65 cm. This air itself is characterized by an elevated – up to 35%, oxygen content (now 21%).

      In the Perm period (Perm, the name of the Russian city in the vicinity of which this stage is allocated) the continents unite again, somewhat differently, forming a single Pangea – washed by the unified world ocean of the Pantalassa. Later, in the Jurassic period of the next era, it will split into six continents known to us. This geological process is characterized by a decrease in the area of inland water bodies, the onset of deserts. Sandy barkhans cover almost the entire territory of present-day Siberia. Carboniferous deposits (coal) overlap with Triassic (motley sandstone, shell limestone).

      The successes of the speciation of Perm are rather modest – several new species of insects. The period ends with the largest in the history of the Earth, the Permian-Triassic extinction (English The Great Dying), 252 million years ago. In less than 60 thousand years, 96% of marine species, 70% of terrestrial vertebrates and 83% of the whole class of insects perish. The main hypotheses of the causes of the event: 1 – the fall of an asteroid a few tens of kilometers in diameter. The crater near Wilkes land (Antarctica, a site with a 300 km ring anomaly opposite Australia) seems to confirm this version. 2 – the release of greenhouse gas from, until the rest at the bottom, at the earth’s poles, frozen methane hydrates. In this case, the world ocean boils, permeated with bubbles, like champagne, freed from cork, giving out about 4 trillion tons of methane to the atmosphere in less than a period of ordinary human life. The weather is going crazy, sharp (more than 6Сº per year) warming is replaced by cold snaps, and this is completely out

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