Simpson, George Gaylord, 1902–84, American paleontologist and zoologist, b. Chicago, Ph.D. Yale, 1926. He became assistant curator of vertebrate paleontology at the American Museum of Natural History in New York City in 1927. From fossil material gathered on trips to the W and SE United States and to Argentina, he discovered migratory and evolutionary patterns of the prehistoric fauna of the Americas. His deductions that species reached adaptive peaks and suffered accidental dispersal contributed greatly to the study of evolution. He served as professor of vertebrate paleontology at Columbia (1945–59) and at Harvard (1959–70). He received many scientific awards. His works include Tempo and Mode in Evolution (1949), The Major Features of Evolution (1953); The Geography of Evolution (1965), and Biology and Man (1969).

Simpson, George Gaylord

(born June 16, 1902, Chicago, Ill., U.S.—died Oct. 6, 1984, Tucson, Ariz.) U.S. paleontologist. He earned a doctorate at Yale University. His contributions to evolutionary theory include a detailed classification of mammals, based on his studies of mammalian evolution, which is still the standard. He also is known for his studies of intercontinental migrations of animal species, especially South American mammals, in past geologic times. His books include Tempo and Mode in Evolution (1944; 1984), The Meaning of Evolution (1949), The Major Features of Evolution (1953), and The Principles of Animal Taxonomy (1961).

Simpson, George Gaylord (1902–84) paleontologist; born in Chicago. After earning a Ph.D. at Yale, Simpson began his long association with the American Museum of Natural History (1927–59), where he was eventually curator of fossil mammals and chairman of the department of geology and paleontology (1942–59). He was later Alexander Agassiz Professor of Vertebrate Paleontology at Harvard (1959–70). Simpson specialized in early fossil mammals, leading expeditions on four continents and discovering in 1953 the 50-million-year old fossil skulls of Dawn Horses in Colorado. He helped develop the modern biological theory of evolution, drawing on paleontology, genetics, ecology, and natural selection to show that evolution occurs as a result of natural selection operating in response to shifting environmental conditions; among his works in this field is the popular Meaning of Evolution (1944, revised 1967).