George Gaylord Simpson (June 16, 1902 – October 6, 1984) was a US paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern synthesis, contributing (1944), Tempo and Mode in Evolution The Meaning of Evolution (1949) and The Major Features of Evolution (1953). He was an expert on extinct mammals and their intercontinental migrations. He anticipated such concepts as  punctuated equilibrium (in Tempo and mode) and dispelled the myth that the evolution of the horse was a linear process culminating in the modern . He coined the word Equus caballus in 1940, and published extensively on the hypodigm taxonomy of fossil and extant mammals. Simpson was influentially, and incorrectly, opposed to  Alfred Wegener's theory of continental drift.
He was Professor of
Zoology at Columbia University, and Curator of the Department of Geology and Paleontology at the American Museum of Natural History from 1945 to 1959. He was Curator of the Museum of Comparative Zoology at Harvard University from 1959 to 1970, and a Professor of Geosciences at the University of Arizona until his retirement in 1982.
In 1943 Simpson was awarded the
Mary Clark Thompson Medal from the National Academy of Sciences. For his work,  Tempo and mode in evolution, he was awarded the Academy's Daniel Giraud Elliot Medal in 1944. He was awarded the  Linnean Society of London's prestigious Darwin-Wallace Medal in 1958. Simpson also received the Royal Society's Darwin Medal 'In recognition of his distinguished contributions to general evolutionary theory, based on a profound study of palaeontology, particularly of vertebrates,' in 1962.
University of Arizona, Tucson, the Gould-Simpson Building was named for Arizona geologist Lawrence M. Gould and Simpson. Simpson was noted for his work in the field of  paleogeography and continental evolution relationships.
In the 1960s, Simpson "rubbished the then-nascent science of
exobiology, which concerned
itself with life on places other than Earth, as a science without a subject".
He was raised as a Christian but later became an
Attending marvels (1931)
(1939) Quantitative Zoology
(1944) Tempo and Mode in Evolution
(1949, 1951) The Meaning of Evolution
Evolution and Geography (1953)
The Major Features of Evolution (1953)
Life: An Introduction to Biology (1957)
Quantitative Zoology (1960)
Principles of Animal Taxonomy (1961)
This View of Life (1964)
The Geography of Evolution (1965)
Concession to the Improbable (1978) (an autobiography)
Fossils and the History Of Life (1983)
Splendid Isolation (1980) The Dechronization of Sam Magruder (posthumously published novella, 1996)
^ a b c
Whittington, H. B. (1986). "George Gaylord Simpson. 16 June 1902-6 October 1984". . Biographical Memoirs of Fellows of the Royal Society 32: 526. doi: 10.1098/rsbm.1986.0017. JSTOR 770122. PMID 11621258.
^ Simpson G.G. 1940. Mammals and land bridges.
Journal of the Washington Academy of Sciences 30: 137–163. See Charles H. Smith's website for full text: 
Simpson, G. G. (1940). "Types in modern taxonomy". American Journal of Science. 238 (6): 413–426. Bibcode: 1940AmJS..238..413S. doi: 10.2475/ajs.238.6.413. p. 418.
^ Simpson G.G. 1953.
Evolution and geography: an essay on historical biogeography with special reference to mammals. Oregon State System of Higher Education: Eugene, Oregon.
"Mary Clark Thompson Medal". National Academy of Sciences. Archived from the original on December 29, 2010 . Retrieved . February 15, 2011
"Daniel Giraud Elliot Medal". National Academy of Sciences. Archived from the original on August 1, 2012 . Retrieved . February 15, 2011
Gould-Simpson Building, Univ. of Arizona Archived June 15, 2009, at the Wayback Machine
Anon (2006). "Astrobiology at ten". Nature. 440 (7084): 582. Bibcode: 2006Natur.440Q.582.. doi: 10.1038/440582a. PMID 16572129.
Léo F. Laporte, ed. (1987). . University of California Press. p. 16. Simple Curiosity: Letters from George Gaylord Simpson to His Family, 1921-1970 ISBN . 9780520057920 By his early teens, Simpson had given up being a Christian, although he had not formally declared himself an atheist. At college he began the gradual development of what might best be called positivistic agnosticism: a belief that the world could be known and explained by ordinary empirical observation without recourse to supernatural forces. Ultimate causation, he considered unknowable.
Aronson, J. (2002). " 'Molecules and monkeys': George Gaylord Simpson and the challenge of molecular evolution". History & Philosophy of the Life Sciences. 24 (3–4): 441–465. doi: 10.1080/03919710210001714503.
Gershenowitz, H. (1978). "George Gaylord Simpson and Lamarck". Indian Journal of History of Science. 13 (1): 56–61. PMID 11615952.
Laporte, L. O. F. (1994). "Simpson on species". Journal of the History of Biology. 27 (1): 141–159. doi: 10.1007/BF01058629. PMID 11639257.
Olson, E. C. (1991). "George Gaylord Simpson: June 16, 1902-October 6, 1984". Biographical Memoirs of the National Academy of Sciences. 60: 331–353. PMID 11616139.
Laporte, Léo F. (1991). "George Gaylord Simpson as mentor and apologist for paleoanthropology". American Journal of Physical Anthropology. 84 (1): 1–16. doi: 10.1002/ajpa.1330840102. PMID 2018099. Laporte, L. F. (1983). "Simpson's Tempo and Mode in Evolution revisited". Proceedings of the American Philosophical Society. 127 (6): 365–417. PMID 11611330.