Expert des mammifères éteints et de leurs migrations, Simpson a été l'un des paléontologues les plus influents du XXesiècle, et l'un des plus importants participants à la théorie synthétique de l'évolution dans son domaine de compétence, la paléontologie.
George Gaylord Simpson est devenu membre étranger de la Royal Society le . Simpson a également reçu la médaille Darwin de la Royal Society "en reconnaissance de ses contributions remarquables à la théorie générale de l'évolution, basées sur une étude approfondie de la paléontologie, en particulier des vertébrés" en 1962. En 1966, Simpson a reçu le Golden Plate Award de l'American Academy of Achievement[3].
1953: Evolution and Geography: An essay on historical biogeography, with special reference to mammals, Oregon State System of Higher Education, Eugene (Oregon): 64 p.
1961: Principles of Animal Taxonomy, Columbia University Press (New York): xii + 247 p.
1965: The Geography of Evolution, Chilton Books, Philadelphia, New York: 249 p.
1977: Too many lines: The limits of the Oriental and Australian zoogeographic regions, Proceedings of the American Philosophical Society, Vol.121, No.2, April 29, 1977, p.107-120.
1980: Why and how: Some problems and methods in historical biology, Pergamon (Oxford): viii + 263 p. (ISBN0080257852)
1984: Discoverers of the lost world: An account of some of those who brought back to life South American mammals long buried in the abyss of time, Yale University Press (New Haven, Connecticut): viii + 222 p. (ISBN0300031882)
Jay D. Aronson (2002). «Molecules and monkeys»: George Gaylord Simpson and the challenge of molecular evolution, History and Philosophy of the Life Sciences, 24 (3/4): 441-465. (ISSN0391-9714)
Joseph Allen Cain (1992). Building a temporal biology: Simpson's program for paleontology during an American expansion of biology, Earth Sciences History: Journal of the History of the Earth Sciences Society, 11: 30-36. (ISSN0736-623X)
Joseph Allen Cain (2002). Epistemic and Community Transition in American Evolutionary Studies: The «Committee on Common Problems of Genetics, Paleontology, and Systematics» (1942-1949), Studies in History and Philosophy of Biological and Biomedical Sciences, 33C: 283-313. (ISSN1369-8486)
Joseph Allen Cain (2003). A Matter of Perspective: Multiple Readings of George Gaylord Simpson's Tempo and Mode in Evolution, Archives of Natural History, 30: 28-39. (ISSN0260-9541)
Joseph Allen Cain (2004). Short Notes: Missing Items from Published Bibliographies for George Gaylord Simpson, Archives of Natural History, 31: 353-355. (ISSN0260-9541)
Harry Gershenowitz (1978). George Gaylord Simpson and Lamarck, Indian Journal of History of Science, 13: 56-61. (ISSN0019-5235)
Léo F. Laporte (1991). George Gaylord Simpson as mentor and apologist for paleoanthropology, American Journal of Physical Anthropology, 84 (1): 1-16. (ISSN0002-9483)
Léo F. Laporte (1994). Simpson on species, Journal of the History of Biology, 27: 141-159. (ISSN0022-5010)
Léo F. Laporte (2000). George Gaylord Simpson: paleontologist and evolutionist, Columbia University Press: xvi + 332 p. (ISBN0-231-12065-6)
Everett C. Olson (1991). George Gaylord Simpson, June 16, 1902—October 6, 1984, Biographical Memoirs of the National Academy of Sciences, 60: 331-353. (ISSN0077-2933)
Harry Blackmore Whittington (1986). George Gaylord Simpson, 16 June 1902–6 October 1984, Biographical Memoirs of Fellows of the Royal Society, 32: 527-539. (ISSN0080-4606)