Borisyak Alexei( Distinguished paleontologist)
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Biography Borisyak Alexei
The name of the scientist linked the new stage of development of paleontology in this country. Starting work on the paleontology of Geolkoma, A. A. Borisyak interested in vertebrate paleontology since opening in 1908. hipparion fauna in Sevastopol. Description of this fauna was dedicated to articles and monographs. In the future, based on new materials A. A. Borisyak began studying the various groups of mammals. His interests have focused on the Paleogene and Neogene mammals from detected many expeditions filled under his leadership. The study examined a. A. Borisyak steel neparnopalye and parnopalye ungulates from sredneoligotsenovoy, so-called 'Paraceratherium-ing' Fauna of Kazakhstan. He studied different groups of rhinos and halikoteriev - a kind of ancient relatives of horses. Number of his works were devoted proboscidian - mastodons, rhinos and horses from the Miocene fauna of Kazakhstan and North Caucasus. In addition, he studied rhinos - Elasmotherium, cave bears and walrus fossils from the later, the Quaternary sediments of different areas of the country.
A. A. Borisyak was a disciple and associate of outstanding national geologist and paleontologist A. P. Karpinski and ideological successor in. O. Kovalevsky. Number of his works is brilliant paleobiologichesky analysis of fossil organisms, carried out by the method, first developed in. O. Kovalevsky. An example of such a study could serve as his monograph on halikoterii - a kind of neparnopalom hoofed from Tertiary deposits (late Oligocene - early Miocene) of Central Kazakhstan. Although halikoterii are neparnopalym, but instead of claws and hooves are a number of features in the structure of the skeleton, strongly distinguish this group from all members of ungulates, making it difficult to restore its ecology. Halikoterii had a long neck, elongated front legs and short, massive rear; brush limbs of three-and tetradigitate, claws are particularly well developed in the forelimb. Using the method of comparative descriptions proposed in. O. Kovalevsky, A. A. Borisyak able to recover the detailed structure and features halikoteriya.
Skull halikoteriya solipeds retains primitive features, such as tapirs, but it has some features. Cervical vertebrae are elongated and their bodies are reduced, while the neural arches are strongly developed. This structure shows a strong development of the muscles of the neck and back, but relatively weak development of abdominal muscles. This development not characteristic of all the muscles neparnopalym Ungulate. In the brush halikoteriya of four of her fingers, only three articulated with the wrist, and the outer, the fifth finger is less than the others and have the most specialized forms of articulated directly with the upper part of the neighboring finger. Such a structure is not observed in none of the mammal. The lower ends of the metacarpal bones represent a spherical surface, like a predator. The first phalanx of second finger metacarpal bone articulated with an unusual way: articular area for a junction with her biased to the front of the phalanx. Thus, the metacarpal bone and first phalanx articulate a right angle. The second phalanx is often fused with the first, and claw also articulated with the first phalanx of right angle. Double bent at right angles, finger serves as a powerful hook, rolling on the metacarpal bones and phalanges of other fingers have the same features only weakly expressed. Wrist low, with large, big bone. On the front side of the bottom row of wrist bones and the front wall of the upper ends of metacarpal bones are strongly expressed by the roughness. They demonstrate the strong development of the extensor muscles of the forelimb. Articulated wrist with the forearm represents the arc and allows the swaying motion of the brush. The structure of the scapula shows a greater development of the anterior muscle. Typically in mammals, more developed flexor forelimb. And back muscle
Shoulder. Thus, the structure of the forelimb halikoteriya shows characteristics opposite to the normal structure of the mammalian limb. Hind legs shorter and more massive, three-toed foot, with the most advanced third finger, shortened metatarsals, phalanges specialization less pronounced than in the brush.
A. A. Borisyak found that the signs of extreme specialization evolved from pozdneoligotsenovyh halikoteriev gradually, through a chain of less specialized Eocene and Oligocene ancestors. Morpho-functional analysis of the peculiarities of the skeleton showed that the head of the animal's neck is not pulled forward and down, as in other ungulates, and up and back to back, and when you move the forelimb its main effort was under way forward, not backward. Borisyak came to the conclusion that such movements are necessary in an animal if his body is in an upright position. He gave the reconstruction halikoteriya, which stands upright, leaning upper limbs of a tree trunk, just as it does a goat when he wants to eat the leaves of trees.
. When vzbrasyvanii front legs, moving the trunk of a tree, will operate the front muscles (extensors) of the entire limb, from wrist to shoulder
. His head is lifted up and slant off back to capture the highest and most distant from the stem leaves, so that the neck is bent to the back. For clinging-walking in the trunk of a well-suited brush halikoteriya. Claw of the second finger is a powerful hook, which is the more digging in the trunk of the tree, the greater the weight it presses. The remaining fingers helps keep the bark, they are very mobile, and individually can change our position and detach. Strong extensor forelimb not just throw it up, but also strengthen the wrist and an elbow joint, preventing podgibaniyu. Articulation of the forearm with a brush along the arc of the lateral movements contribute to the brush, which is adjustable to most comfortable position on the trunk.
In this situation the animal's body stood on its hind legs, so they are 'built' like a heavy forms, in contrast to the fine bones of the rest of the skeleton. Bones of hind limbs massive, astragalus is flattened and shifted to the cubic, metatarsal bones were shortened, the entire three-toed foot and less specialized than the brush. Summing up the work, A. A. Borisyak wrote that paleobiologichesky analysis puts the task of evaluation of evidence, which leads to the two categories. The first - characteristics inherited from their ancestors, going through all the representatives of this group. Second - signs of increasing specialization in the process of adaptation to the conditions in which there is this group. These features allow the present lifestyle of extinct animals and restore the biological type. Since specialization halikoteriev manifested in varying degrees from their more ancient representatives of the successive geological layers, . then paleontology at its material can reconstruct the process of formation of biological type, . trace it step by step, . stage for stage.,
. A. Borisyak laid a solid foundation in the USSR vertebrate paleontology. In 1930. he organized the Paleontological Institute of the Academy of Sciences. Since then, work on palaeontology become systematic and purposeful. The main activity of the Paleontological Institute, USSR Academy of Sciences, headed by academician A. A. Borisyak, was aimed at the development of evolutionary paleontology, based in. O. Kovalevsky. The institute had conducted an extensive study on the morphology, taxonomy, phylogeny and the laws of historical development of many groups of invertebrates and vertebrates.
Academic A. A. Borisyak able to focus at the institute best scientific forces of the country. With him working with such outstanding domestic paleontologists as Academician P. P. Sushkin AND. A. Efremov, Yu. A. Orlov, K. K. Flerov and others, for his work developing an evolutionary trend in the science of fossil. Expanded and field studies on paleontology. A. A. Borisyak and his staff at the Paleontological Institute NW. A. "Orlov,. A. Efremov and others engaged in the continental sediments of the Soviet Union, and described more than a dozen previously unknown vertebrate faunas of the Permian, Triassic and Tertiary. Activity A. A. Borisyak and his staff had a great influence on the development of new research centers in the palaeontology Academies of Sciences of the Union Republics. Proceedings of Soviet scientists have raised at high altitude national science of fossil animals, which significantly affected the development of world science.
Following in. O. Kovalevsky A. A. Borisyak walked towards paleontologist, evolutionist, defending and developing this area. The result of his thoughts for nearly half a century of work in paleontology Academy A. A. Borisyak outlined in his essay 'The main problem of evolutionary paleontology', which was published after his death in 1947. In this great work he has developed creative ideas in. O. Kovalevsky and carefully considered a number of problems evolutionary paleontology. This essay is a program of Soviet paleontologists. He identified three major challenges of evolutionary paleontology: the relationship of the organism and environment; phylogenesis (this issue also included the issues of relations phylogenesis and ontogenesis, t. e. historical and individual development), and morphogenesis, or speciation. Further activities of domestic paleontologists focused on the development goals.