Mesozoic era. A Triassic.

The Triassic on the Earth proceeded about 45 million years. From its beginning up to now has driven approximately 220 million years. In a trias the land prevailed over the sea. There were two continents. The North Atlantic among themselves North Atlantic and Asian continents have formed Northern land. In southern, a hemisphere former Gondwana laid. Asia has incorporated to Australia and New Zealand. All Southern Europe, caucasus and Crimea, Iran, the Himalayas and the North Africa has been filled in by ocean to the Aunt. The big mountain chains at this time anew did not arise, but the mountains generated during the former periods, were still high. Often there were volcanic eruptions. The Triassic climate was sharp and dry, but warm enough. Deserts in a trias are numerous.

From plants gymnosperms considerably prevailed: cycads, coniferous and Ginkopsida. From seed ferns the glossopteris continued to exist. In the end of the period there were original ferns, especially numerous in the subsequent Jurassic which leaflets on a nervation reminded leaves of seed plants. Triassic horsetails stand much more close to modern horsetails, than Paleozoic.

In a life of inhabitants of continents there Were main recesses. Begun in a Permian prevalence of a land over the sea and progressive drainage of many fresh reservoirs in a Triassic have led to that many fresh-water fishes have moved now in the seas, and only dipnoan, close to present, former lived in the escaped fresh-water basins. In the end of a Triassic Stegocephalias have died out. It were last representatives of the Labyrinthodontia Stegocephalias named so because enamel on their teeth had a difficult folded structure. All Stegocephalias, being rescued from an arid climate and from a competition to reptiles, became water, and some even have passed to live in the sea. The majority of them were very large animals. For example, at the Mastodonsaurus the length of a skull reached 1 m.

In the Triassic beginning there lived immediate ancestors of modern frogs. These Protobatrachus fine, length 10 sm, animal, on the general warehouse remind toads, than the present frogs more likely. Their skin lumpy, hind legs are more adapted for swimming, than for a jump.

Reptiles have especially strongly changed: Cotylosauria definitively died out. In second half of period there were first turtles at whom unlike modern in the sky a teeth while jaws have been dressed by a horn beak have still remained.

In a Triassic strenuously developed, but in the end of it last theroid reptiles have already died out. From them herbivorous and already absolutely edentate Stahleckerias reached the sizes of a large rhinoceros.

The fine theromorphs reptiles Ictiosaurio close to mammals are especially interesting. So, caromis, the animal in size about a rat, on a structure of the skull already is the present mammal, and only the additional bones which are available in its bottom jaw, specify that this animal still a reptile.

From other reptiles in Triassic the period rhynchocephalia, nearest relatives of a modern New Zealand tuatara who though are similar to customary lizards developed, but differ from them on the structure. The tuatara in the structure has kept till now many ancient features. In its skull there are two temporal (malar) arches, instead of one, as for lizards. The top jaw at it hangs down downwards in the form of a small beak. A teeth on jaws sits not in separate cells, and in the general fillet. Except customary edges, on a belly "belly edges" develop still. Biconcave vertebras remind vertebras of fishes. Among rhynchocephalia in a trias lived - large digging animals, probably, eating roots. In the seas, on coast of continents, came across halfbeak rhynchocephalia - fighters of sea molluscs. In a place with them behind molluscs placodonts resembling sea turtles at which in the sky instead of a fine teeth the present millstones for a crush of bowls were formed hunted. Related to placodonts nothosaurs too conducted a water way of life. These long-necked animals still could use the paws (fins) for circulation by the ground. From nothosaurs there were plesiosauri, customary sea reptiles of following periods. In northern waters there were first ichthyosauri. They yet so have well been adapted for swimming in the sea, as their descendants at whom the tailing became similar to the fish. The most remarkable that ichthyosauri did not postpone some eggs as customary reptiles, and gave rise to live cubs, like mammals. Blossoming of group of Cell-tooth reptiles has begun with a trias. The most ancient forms from them were rather small carnivores. Instead of customary movement on four feet these animals adapted to circulation and on two in this connection their hind legs became much longer than lobbies. The Saltoposuchus was such, the animal in the size is more 1 m. By the trias end some Cell-tooth reptiles have passed to a water way of life. They have again started to go on four feet and on appearance resembled still absent then crocodiles. The length such a crocodile-shaped of the prestosuchus was not less than 5 m. Mainly on Northern land there were the first, yet very big on the size are rare dinosaurs. Some of them were not insignificant, to 1м at length, and conducted a predatory way of life. Went on hind legs which were longer than lobbies. To some signs dinosaurs reminded birds: bones of their skeleton were hollow filled with air, and the first finger on back a foot has been turned back.

Other dinosaurs, for example a Plateosaurus, were much larger, reaching 6 m at length. The difference in a structure of lobbies and hind legs at them is insignificant, a teeth stupid. It were ancestors of herbivorous giants of a Jurassic.

It is no wonder, that at an abundance in a trias of theromorphs reptiles we find here and the present mammals. The most ancient mammal known to us, size from a marmot, is called "Tritilodontia". It concerns group many the bunodont mammals named so because at them on molars in two or three numbers numerous cones have been located. Canines at them was not. One steam of chisels in the top jaw and unique pair in the bottom have been increased. Much bunodont ate vegetative food. Possibly still postponed eggs, instead of gave rise to live Cubs, as well as modern Australian single-pass mammals: a duck-bill also it is malicious. Modern oviparous mammals - anodontous, but germs of a duck-bill have rudiments of a teeth of multilumpy type. Therefore much the bunodont consider as the nearest relatives Australian single-pass, at which else many features, characteristic for reptiles remain.

At the bottom of the Triassic sea there lived the numerous six-beam corals close to the modern. Plentiful were folding and gastropodses which replaced brachiopods. New sea hedgehogs and lilies often came across. But an especial variety in this period reached numerous ammonites. During same time there were first belemnites - the animals close to modern sea cuttlefishes, too concerning cephalopods to molluscs. Under a skin at them the limy skeleton in a kind to a plate, coming to an end has been hidden by a sharp thorn. This thorn usually remains in a fossil condition and "the devil's finger" is called.

In the sea, except squaloid fishes, already lived a lot of bone which ancestors have moved here from fresh water. Here there were Crossopterygiis of fish and relatives of modern, sturgeon fishes, and also armour-clad pikes and mudfishes the North America. On a structure of scales, a tailing and internal bodies these fishes still differed from the present bony fishes.