Joseph John Sepkoski Jr. (July 26, 1948 – May 1, 1999) was a
University of Chicago paleontologist. Sepkoski studied the fossil record and the diversity of life on Earth. Sepkoski and
David Raup 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
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
66
mya
Mya may refer to:
Brands and product names
* Mya (program), an intelligent personal assistant created by Motorola
* Mya (TV channel), an Italian Television channel
* Midwest Young Artists, a comprehensive youth music program
Codes
* Burmese ...
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. In 1970, Sepkoski received a B.S. degree, magna cum laude, from the
University of Notre Dame. 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. Gould sp ...
he earned a Ph.D. in geological sciences from
Harvard University in 1977. His Ph.D. was on the field geology and paleontology of the
Black Hills of
South Dakota. From 1974 to 1978, Sepkoski taught at the
University of Rochester. 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 Faunas 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 anima ...
. 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'',
Paleontological Society
* Elected foreign member of the
Polish Academy of Sciences
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 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