Joseph John Sepkoski Jr.(July 26, 1948 – May 1, 1999) was aUniversity of Chicagopaleontologist.Sepkoski studied the fossil record and the diversity of life on Earth. Sepkoski andDavid Raupproduced a new understanding ofextinction events,by developing a statistical approach to the study of taxonomic diversification. He suggested that theextinction of dinosaurs66myawas part of a cycle of mass extinctions that may have occurred every 26 million years. But his most important contribution was the identification of the "Big 5" mass extinctions, events that have shaped the evolution of life on earth.
Life and work
editSepkoski was born inPresque Isle, Maine.In 1970, Sepkoski received a B.S. degree,magna cum laude,from theUniversity of Notre Dame.UnderStephen Jay Gouldhe earned a Ph.D. in geological sciences fromHarvard Universityin 1977. His Ph.D. was on the field geology and paleontology of theBlack HillsofSouth Dakota.From 1974 to 1978, Sepkoski taught at theUniversity of Rochester.In 1978, he joined the University of Chicago and became a professor in 1986. Sepkoski was also a research associate at theField Museum of Natural Historyin Chicago. He died of heart failure related tohigh blood pressureat the age of 50.
Sepkoski is perhaps best known for his global compendia of marine animal families and genera, data sets that continue to motivate a tremendous amount of paleobiological research. Sepkoski himself explored his compendium very thoroughly. In 1981, he identified three greatEvolutionary Faunasin the marine animal fossil record. Each of his Evolutionary Faunas, the Cambrian, Paleozoic, and Modern Faunas, is composed of Linnean classes of animals that have covarying diversity patterns, characteristic rates of turnover, and broadly similar ecologies. Most importantly, they sequentially replaced one another as dominant groups during thePhanerozoic.Sepkoski modeled the Evolutionary Faunas using three coupledlogistic functions,but the underlying drivers of the prominent shift in taxonomic composition represented by the three faunas remains unknown.
Sepkoski was married to paleontologistChristine Janis,a specialist in fossil mammals. His son (from a previous marriage) is the historian of scienceDavid Sepkoski.
Awards
edit- (1983).Charles Schuchert Award,Paleontological Society
- Elected foreign member of thePolish Academy of Sciences
Selected publications
edit- Sepkoski, J. John Jr. (1978). "A kinetic model of Phanerozoic taxonomic diversity. I. Analysis of marine orders".Paleobiology.4(3):223–251.doi:10.1017/s0094837300005972.JSTOR2400203.S2CID87102033.
- Sepkoski, J. John Jr. (1979). "A kinetic model of Phanerozoic taxonomic diversity. II. Early Phanerozoic families and multiple equilibria".Paleobiology.5(3):222–251.doi:10.1017/s0094837300006539.JSTOR2400257.S2CID89475468.
- Sepkoski, J. John Jr. (1981). "A factor analytic description of the Phanerozoic marine fossil record".Paleobiology.7(1):36–53.doi:10.1017/s0094837300003778.JSTOR2400639.S2CID133114885.
- Raup, David M.;Sepkoski, J. John Jr. (19 March 1982). "Mass extinctions in the marine fossil record".Science.215(4539):1501–3.Bibcode:1982Sci...215.1501R.doi:10.1126/science.215.4539.1501.PMID17788674.S2CID43002817.
- Sepkoski, J. John Jr. (1984). "A kinetic model of Phanerozoic taxonomic diversity. III Post-Paleozoic families and mass extinctions".Paleobiology.10(2):246–267.doi:10.1017/s0094837300008186.JSTOR2400399.S2CID85595559.
- Raup, David M.; Sepkoski, J. John Jr. (Feb 1984)."Periodicity of extinctions in the geologic past".Proceedings of the National Academy of Sciences of the United States of America.81(3):801–805.Bibcode:1984PNAS...81..801R.doi:10.1073/pnas.81.3.801.PMC344925.PMID6583680.
- Sepkoski, J. John Jr. (1988). "Alpha, beta, or gamma: where does all the diversity go?".Paleobiology.14(3):221–234.doi:10.1017/S0094837300011969.JSTOR2400884.PMID11542147.S2CID2826581.
- Sepkoski, J. John Jr. (1996). "Patterns of Phanerozoic extinction: a perspective from global data bases". InOtto H. Walliser(ed.).Global Events and Event Stratigraphy.Berlin: Springer. pp.35–51.doi:10.1007/978-3-642-79634-0_4.ISBN978-3-642-79636-4.
- Sepkoski, J. John Jr. (2002). "A compendium of fossil marine animal genera".Bulletins of American Paleontology.363.Ithaca, NY:Paleontological Research Institution:1–560.ISBN978-0-87710-450-6.
Further reading
edit- "Sepkoski, J. John, Jr.".American National Biography.Oxford University Press.Subscription needed.
External links
edit- Miller, Arnold. (Sep. 1999).Memorial: J. John Sepkoski, Jr.: A personal reflectionArchived2007-02-07 at theWayback Machine.Journal of Paleontology.
- NASA,Near Earth ObjectProgram
- Sepkoski's Online Genus Database