ORLOV, YURI ALEKSANDROVICH

(b. Tomyshevo, Russia, 13 June 1893; d. Moscow, U.S.S.R., 2 October 1966)

histology vertebrate paleontology.

Orlov was the son of Alexander Fyodorovich Orlov, an employee of the Forest Department. In 1911 he entered the Physical-Mathematical Faculty at Petersburg University. He specialized in histology under A.S. Dogel, In 1916 he was invited by A.A. Zavarzin to hold the post of assistant in the Faculty of Histology and Embryology of the newly opened University of Perm. From 1925 to 1935 Orlov worked in the department of histology and embryology, headed by Zavarzin, of the Military Medical Academy in Leningrad, where his renewed love of paleontology led him to take part in paleontological field researches. His first field work, in 1925, was at the excavations of Neocene and Quaternary mammals in western Siberia and northwestern Kazakhstan.

In 1930 Orlov began scientific work at the new Paleontological Institute of the U.S.S.R. Academy of Sciences. In 1936 the institute moved to Moscow, and after that time Orlov’s career was completely dedicated to paleontology. Orlov became the first manager of the institute’s museum. In 1939 he was named head of the department of paleontology at Moscow University, and in 1945, after A.A. Borissiak’s death, he was made director of the Paleontological Institute. Orlov’s scientific organizing activity was quite successful and many-sided. He was one of the organizers of the Mongolian paleontological expedition of the U.S.S.R Academy of Sciences (1946–1949) and of the joint Soviet-Chinese paleontological expedition (19597–1960).

In 1953 Orlov was elected a corresponding member of the U.S.S.R. Academy of Sciences, and in 1953 he became a full member. He was the editor in chief of the fifteen-volume Fundamentals of Paleontology. He visited many foreign countries, participating in international congresses and symposia. Orlov was an honorary member of the Moscow Society of Naturalists, the All-Union Paleontological Society the Associación Paleontológica Argentina, the American Society of Vertebrate Paleontology, the Geological Society of London, and many others. He promoted the consolidation of relationships between many scientists in different countries, as was acknowledged in an honorary diploma from the Soviet Peace Committee. He was awarded the gold medal of the Paleontological Society of India.

Orlov’s scientific activity can be divided into two main periods. In the first period, up to the end of the 1920’s he conducted his research mainly on comparative invertebrate systematics; in the second period he concentrated on paleontology. Orlov made a valuable contribution to the problem of neuron organization of the nervous system of arthropods. He established an important parallel between the structures of the nervous systems in arthropods and vertebrates, expressed particularly in the presence of a detachable third neuron between the sensory and motor neurons of the reflex arc. Orlov’s paleontological researches focused mainly on Neocene mammals. In his first such works, published between 1927 and 1930, he describes fossil camels of northwestern Kazakhstan.

Orlov also wrote a series of works on fossil carnivores: saber-toothed cats, ichthyosaurs, hyenas, badgers, martens, and otters. These works raised the study of fossil mammals in the Soviet Union to a new level and have retained their essential importance. Among Orlov’s works on carnivores are those on the giant marten, which he named perunium, from the Meotian of Moldavia (Grebenniki village), and on the otterlike carnivorous Semantor from the hipparion fauna of Pavlodar, Orlov classified the Semantor, known only from posterior parts of the skeleton and the shoulder bone, as a connecting link between otters and seals. He categorized it as Pinnipedia, within which he distinguished a new family, Semantoridae, more primitive, than Otariidae. Semantor is now classified not as Pinnipedia but directly as martens (Mustelidae); the recent seals (Phocidae) are known from more ancient deposits than Semantor (the middle Miocene).

Semantor’s adaptations show the course of formation of specialalized pinniped auatic carnivores. In Orlov’s opinion Perunium, described from a skull 20 centimeters long, demonstrated the combination of some adaptations of the largest mustelids—gluttons (Gulo) and bears. This conception was reflected in the species denomination for Perunium—Pursogulo—offered by Orlov who classified it as a special subfamily of mustelids, to which he related the large fossil honey eaters of the genus Eomellivora. This placement was unsuccessful, and Perunium is now classified as an ordinary mustelid, related to the genus, Plesiogulo, known from the Pliocene of China and North America. Orlov’s detailed biological analysis of the cerebral structure of Perunium was a great importance; the external morphology was described in details from the cast of the skull cavity.

Orlov’s last major work of paleontology, published in 1958, addressed Upper Permian carnivorous deinocephalian fauna from the Ishejev locality (Middle Volga). This work is one of the best ever on the descriptive morphology of deinocephalians. Orlov also published many articles of a general character, including one on the tasks of studies in the field of paleoneurology of vertebrates (1949). He was interested in history of science and published articles on the lives and activities of Russian scientists, such as A.A. Inostrantsev, V.P. Amalitskii, A.A. Borissiak, V.A. Obruchev, and A.P. Bystrov.

During the last years of his life, Orlov paid much attention to the popularization of science. His book In the World of Ancient Animals, illustrated by K.K. Flerov, was published twice in the Soviet Union (1961 and 1968). Orlov wrote about two hundred publications.

BIBLIOGRAPHY

Orlov’s important works include “Semantor macrurus (ordo Pinnipedia, fam. Semantoridae fam. nov.) aus den Neogen-Abangerungen Westsibiriens”, in Trudy Paleontologicheskikh instituta Akademüa nauk SSSR 2 (1933), 165–268 (in Russian); “Fundort der Hipparion-Fauna am Irtysch in der Stadt Pavlodar (W. Sibiriens)”, ibid., 5 (1936), 155–169 (in Russian); “Teriäre Raubtiere des westliechen Sibiriens. I Machairodontidae”, ibid., 5 111–152 (in Russian); “Peruniinae, novoje podsemeistvo kunitziz reogena Evrazii (k filogenii kunitz)”, ibid., 8 , no. 2 (1941); “Tretichnie hischniki Zapadnoi Sibiri. 2. Barsuki.3. Kunitzi. 4. Gieni. 5 Iktiterii”, ibid., no.3; “Hischnie deinotzefali fauni Isheeva (titanozuhi)”, ibid., 72 (1958); and V mire drevnih zivotnih (Moscow, 1968).

Leonid Tatarinov