Joseph John Sepkoski Jr. (July 26, 1948 – May 1, 1999) was a
University of Chicago
The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
. Sepkoski studied the fossil record and the diversity of life on Earth. Sepkoski and
David Raup
David M. Raup (April 24, 1933 – July 9, 2015) was a University of Chicago paleontologist. Raup studied the fossil record and the diversity of life on Earth. Raup contributed to the knowledge of extinction events along with his colleague Jack S ...
contributed to the knowledge of
extinction event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
s. They suggested that the
extinction of dinosaurs 66
mya was part of a cycle of mass extinctions that may have occurred every 26 million years.
Life and work
Sepkoski was born in
Presque Isle, Maine
Presque Isle is the commercial center and largest city in Aroostook County, Maine, United States. The population was 8,797 at the 2020 Census. The city is home to the University of Maine at Presque Isle, Northern Maine Community College, Hus ...
. In 1970, Sepkoski received a B.S. degree, magna cum laude, from the
University of Notre Dame
The University of Notre Dame du Lac, known simply as Notre Dame ( ) or ND, is a private Catholic research university in Notre Dame, Indiana, outside the city of South Bend. French priest Edward Sorin founded the school in 1842. The main c ...
. Under
Stephen Jay Gould
Stephen Jay Gould (; September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was one of the most influential and widely read authors of popular science of his generation. Goul ...
he earned a Ph.D. in geological sciences from
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of highe ...
in 1977. His Ph.D. was on the field geology and paleontology of the
Black Hills
The Black Hills ( lkt, Ȟe Sápa; chy, Moʼȯhta-voʼhonáaeva; hid, awaxaawi shiibisha) is an isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, United States. Black ...
of
South Dakota
South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large po ...
. From 1974 to 1978, Sepkoski taught at the
University of Rochester
The University of Rochester (U of R, UR, or U of Rochester) is a private research university in Rochester, New York. The university grants undergraduate and graduate degrees, including doctoral and professional degrees.
The University of ...
. In 1978 he joined the University of Chicago and became a professor in 1986. Sepkoski was also a research associate at the
Field Museum of Natural History
The Field Museum of Natural History (FMNH), also known as The Field Museum, is a natural history museum in Chicago, Illinois, and is one of the largest such museums in the world. The museum is popular for the size and quality of its educational ...
in Chicago. He died of heart failure related to
high blood pressure
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
at 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 great
Evolutionary Fauna
The concept of the three great evolutionary faunas of marine animals from the Cambrian to the present (that is, the entire Phanerozoic) was introduced by Jack Sepkoski in 1981 using factor analysis of the fossil record. An evolutionary fauna typic ...
s in 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 the
Phanerozoic
The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 538.8 million years to the present, and it began with the Cambrian Period, when anim ...
. Sepkoski modeled the Evolutionary Faunas using three coupled
logistic function
A logistic function or logistic curve is a common S-shaped curve (sigmoid curve) with equation
f(x) = \frac,
where
For values of x in the domain of real numbers from -\infty to +\infty, the S-curve shown on the right is obtained, with the ...
s, but the underlying drivers of the prominent shift in taxonomic composition represented by the three faunas remains unknown.
Sepkoski was married to paleontologist
Christine Janis, a specialist in fossil mammals. His son (from a previous marriage) is the historian of science
David Sepkoski.
Awards
* (1983). ''
Charles Schuchert Award
The Charles Schuchert Award is presented by the Paleontological Society to a person under 40 whose work reflects excellence and promise in the science of paleontology. The award was made in honor of Charles Schuchert (1858 – 1942), an American ...
'',
Paleontological Society
The Paleontological Society, formerly the Paleontological Society of America, is an international organisation devoted to the promotion of paleontology. The Society was founded in 1908 in Baltimore, Maryland, and was incorporated in April 1968 in ...
* Elected foreign member of the
Polish Academy of Sciences
The Polish Academy of Sciences ( pl, Polska Akademia Nauk, PAN) is a Polish state-sponsored institution of higher learning. Headquartered in Warsaw, it is responsible for spearheading the development of science across the country by a society o ...
Selected publications
*
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Further reading
* ''Subscription needed.''
External links
* Miller, Arnold. (Sep. 1999).
Memorial: J. John Sepkoski, Jr.: A personal reflection ''
Journal of Paleontology''.
NASA Near Earth Object
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
Program
Sepkoski's Online Genus Database
{{DEFAULTSORT:Sepkowski, Jack
1948 births
1999 deaths
American paleontologists
University of Notre Dame alumni
Harvard University alumni
University of Rochester faculty
University of Chicago faculty
People from Presque Isle, Maine