Otniel Charles Marsh is a US paleontologist. During 1861–1899 he had published almost 300 works (articles, reports and books), described 225 new genera, 469 species, and 64 families. Competition with the American Paleozoologist Edvard Kop grew into the so-called "War of Bones", which promoted public interest to dinosaurs and many discoveries in the field of Paleozoology and evolution.

O. Ch. Marsh was the first professor of paleontology in America. Publications of his first scientific works, he started in 1861. At this time, he became an organizer of the first expedition, equipped for the special purpose of collecting fossil vertebrate animals. This expedition carried out a paleontological excavation in the western states of the USA. As a result of this activity, O. Marsh published a number of small articles on fossil vertebrates and two large Palaeozoic works: A value monograph on the fossil-toothed birds (Odontoornites) (1880), And also the great monograph devoted to the wonderful group of Eocene ungulates (Dinocerata) (1885).

Considerable importance came to the discovery by O. Marsh in 1872 toothy birds of Cretaceous deposits of Kansas. In general, Fr. Marsh has found many new forms. Some of the published genera were widely known. For example, Dinosaurs: Atlantosaurus, Drontosaurus, Diplococus and Stegosaurus. Horned dinosaurs: Triceratops and Torosaurus, pterosaurs, representatives of the Equidae family: Eohippus, Mesohippus, Orohippus, Pliohippus, titanotheriidae: Brontops and Brontotherium and many other. Their listing in the book about Marsh, written by Shukhter and M. Le-Ven occupies seven pages.

Scientific heritage O. Marsh is very large. He opened new families, even genera of mammals, birds and reptiles. He gave the classical restoration of the representatives of three mammal classes studied by him. March did a lot to study the ancient Upper Jurassic and Upper Cretaceous mammals of Colorado and Wyoming. Particular note is on his merits in the field of studying the genealogy of the Equine family. He described various members of this family found in North America, from the small Eohippus with four fingers on the front limb to the Pleistocene horse Equus. In general, O. Marsh studied many forms of American fossil horses. He established phylogenetic relationships between these forms. However, he could not make a monographic description of this wonderful group of animals. His works doesn't even compare with the classic monograph of our Volodymyr Kovalevskyi on this issue. And this despite the fact that O. Marsh possessed incomparably richer material than V. Kovalevskyi, and he already has the work of our scientist, who proposed a new method of paleontological research. That is why O. Marsh's small articles are mostly of historical interest today, they have a rather honorable place in the archives of the science, and a later monograph by V.O. Kovalevskyi is still a consummate treatise on paleozoological research. The article analyzes the scientific achievements of Otniel Marsh in the field of paleozoology.

1. (2019). Bilya vytokiv «neolamarkizmu»: vydatnyy amerykansʹkyy paleontoloh Edvard Drinker Kop (1840–1897) [At the origins of "neo-Marxism": the famous American paleontologist Edward Drinker Kopp (1840-1897)]. Istoriya nauky i biohrafistyka [History of science and biography]. № 4[in Ukrainian].
2. Othniel Charles March. Encyclopedia Britannica [in English].
3. (1974). Marsh Otniel Marsh. Bol'shaja sovetskaja jenciklopedija [The Great Soviet Encyclopedia]: [v 30 t.] / Pod red. A.M. Prohorova. 3-e izd. Moskva: Sov. jenciklop. Т. 15. С. 429 [in Russian].
4. Маrch O.C. Introduction and succession vertebratelife on America. Amer. Journ. Sci. 1877, (3), Vol. 14. P. 337–378 [in English].
5. Маrch O.C. History and method of paleontological discovery. An address delivered before the American Associacion for the advancement of sciences at Saratoga. N. Y. 1879, August 28 [in English].
6. Маrch O.C. Small size of the brain in Tertiary mammals. Amer. Journ. Sci. 1974, (3), Vol.8, P. 66–67 [in English].
7. Маrch O.C. Recent discoveries of extinct animals. Amer. Journ. Sci. 1976, (3), Vol.12, P. 59–61 [in English].
8. Маrch O.C. Dinocerata: a monograph of an extinct order of gigantic mammals. 1885. 237 p. (Monographia U.S. Geol. Sury. Vol. 10) [in English].
9. Lartet B. De quelques cas de progression organique verfiables dans la succession des temps geologiques sur les mammiferes de meme famille et de meme genre. Comp. Rendus. 1868. Vol. 66. P. 1119–1122 [in English].
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