William Alvin Clemens Jr. (May 15, 1932 — November 17, 2020) was a paleontologist at the University of California at Berkeley. He was faculty of the Department of Paleontology from 1967, then the Department of Integrative Biology from 1994 to his retirement and curator of the UC Museum of Paleontology. Clemens was also director of the museum (1987–1989) and chair of the Department of Paleontology (1987–1989). He was awarded a

Guggenheim Fellowship Guggenheim Fellowships are grants that have been awarded annually since by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the ar ...

(1974–75), a U.S. Senior Scientist Award by the Alexander von Humboldt Foundation, the

Romer-Simpson Medal The Romer-Simpson Medal is the highest award issued by the Society of Vertebrate Paleontology for "sustained and outstanding scholarly excellence and service to the discipline of vertebrate paleontology". The award is named in honor of Alfred S. Ro ...

(2006), and was made a Fellow of the California Academy of Sciences.

Early life and education

Clemens was born in Berkeley, California. After graduating from Berkeley High School, he attended the University of California, Berkeley, earning a B.A. in paleontology in 1954 and a Ph.D. in 1960. From 1961 to 1967, he served as faculty in the Zoology Department at the University of Kansas and as the curator of higher vertebrates in their Museum of Natural History.

Research

Clemens' research focussed on the evolution of

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s in the Mesozoic Era, both their origin and diversification as well as the microstructure of the early mammalian jaw and teeth. He was also noted for his research into the extinction of the dinosaurs at the

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of ...

(K–Pg or K-T boundary). Clemens supported a view contrary to the more familiar Alvarez hypothesis model of sudden catastrophic extinction precipitated by an asteroid, which was proposed in part by Walter Alvarez, also at the University of California, Berkeley, at the time. Clemens' research in western

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

suggests that the dinosaurs were already undergoing gradual extinction prior to the end of the Cretaceous and that other groups of vertebrates were not severely impacted by the event.

Selected publications

* Clemens, William A. (1997). "Characterization of enamel microstructure and application of the origins of prismatic structures in systematic analyses", pages 85–112 ''in'' W. V. Koenigswald (ed.) ''Tooth enamel microstructure''. Rotterdam: A. A. Balkema. * Clemens, William A. (2001). "Patterns of mammalian evolution across the Cretaceous-Tertiary boundary". ''Mitteilungen aus dem Museum für Naturkunde in Berlin, Zoologische Reihe'' 77:175–191. * Clemens, William A. (2002). "Evolution of the mammalian fauna across the Cretaceous-Tertiary boundary in northeastern Montana and other areas of the Western Interior." ''Geological Society of America'', Special Paper 361: 217–245. * Clemens, William A. (2006). ''Ecological diversification of mammals during the Mesozoic, the Age of Dinosaurs''. McGraw-Hill.

References

{{DEFAULTSORT:Clemens, William A. Jr. 1932 births 2020 deaths People associated with the California Academy of Sciences Berkeley High School (Berkeley, California) alumni Writers from Berkeley, California University of California, Berkeley College of Letters and Science faculty American paleontologists Presidents of the Society of Vertebrate Paleontology