October 31, 2014
College of Computer, Mathematical, and Natural Sciences

Bretton W. Kent

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Director of Undergraduate Studies

Contact

Email: bkent@umd.edu
Office Phone: 301-405-3125
Fax: 301-314-9290
Office Address: University of Maryland * Entomology Department * Plant Sciences Building * College Park, MD 20742

Teaching

  • BSCI 207, Principles of Biology III
  • BSCI 392, Biology of Extinct Animals
  • BSCI 393, Biology of Extinct Animals Laboratory
  • ENTM 701, Effective Teaching: TA Training
  • CLFS 510, Concepts in Modern Biology
  • CLFS 609F, Priciples of Paleobiology
  • CLFS 710, Experimental Biology
  • CLFS 725, Experimental Design and Statistics

Graduate Program Affiliations

  • Master of Chemical & Life Sciences Program (Associate Director)

Research Interests

My research is primarily concerned with the shark faunas during the Neogene polytaxic maximum (NPM). The NPM began following a prolonged period of very low global temperatures in the Late Oligocene (Chattian) about 26-27 Mya. By the late Early Miocene (Burdigalian) global temperatures and atmospheric carbon dioxide levels increased until they were comparable to those of today. This period was characterized by a marked diversification and expansion of marine communities. The end of the NPM began with episode of global cooling 3.6-2.0 Mya in the Late Pliocene (Piacenzian) and concluded with a major turnover in marine biotas 2-1 Mya.

During the NPM shark faunas underwent two fundamental changes. The first was faunal modernization where middle trophic levels previously dominated by lamniform sharks with tearing-type teeth (i.e., tall, slender crowns) were replaced by carcharhiniforms with more versatile cutting-clutching dentitions (i.e., serrated, blade-like teeth in the upper jaw and slender, erect teeth in the lower jaw). This rise of the carcharhiniforms appears to have been associated with the diversification of marine invertebrates and teleosts in the tropics beginning in the Late Paleogene and continuing through much of the later Neogene.

The second change in NPM shark faunas was a remarkable burst of gigantism in several distantly-related orders, including the hexanchiforms, lamniforms, and carcharhiniforms. All polytaxic maxima are distinguished by the evolution of an exceptionally large ‘superpredator’, and this role was filled by the enormous megatooth (= giant white) sharks of the genus Carcharocles during the NPM. Gigantism during the Neogene appears to be correlated with a corresponding diversification of advanced cetaceans and pinnipeds. Near the end of the NPM both cetaceans and pinnipeds shifted their centers of diversity to colder, more polar oceans, and the temperate-dwelling giant sharks were left without a reliable food base.

By the Late Pliocene, the NPM was coming to an end; almost all of the gigantic sharks were extinct and essentially modern, carcharhiniform-dominated shark faunas remained.

My current research focuses on the early stages of the NPM (Late Oligocene through Middle Miocene) in the Mid-Atlantic of the eastern United States when many shark taxa where rapidly diversifying and shark faunas were increasing in structural complexity. Fundamental questions, such as the organization and temporal extent of different faunas and the role of the giant sharks in determining the structure of faunas are at present very poorly known, and the goals of my research.

Representative Publications

  • Kent, B. W. 1983. Diet expansion of Busycon contrarium in the absence of Triplofusus giganteus. Nautilus 97: 103-104.
  • Kent, B. W. 1983. Natural history observations on the whelks Busycon contrarium (Conrad) and Busycotypus spiratum (Lamarck). J. Moll. Stud. 49:37-42.
  • Kent, B. W. 1987. Fossil Sharks of Maryland: An Illustrated Guide. Glossopetrae Press, Takoma Park, MD, 52 pp.
  • Kent, B. W. 1992. Making Dead Oysters Talk: Techniques for Analyzing Oysters from Archaeological Sites (2nd edition). Maryland Historical and Cultural Publ., Crownsville, MD, 76 pp.
  • Kent, B. W. 1994. Fossil Sharks of the Chesapeake Bay Region. Egan Rees and Boyer, Inc., Columbia, MD, 146 pp.
  • Kent, B. W. 1996. Biology of Extinct Animals Laboratory Manual. Campus Reprographics, College Park, MD, 162 pp.
  • Kent, B. W. and G. W. Powell, Jr. 1998. Reconstructed dentition of the rare lamnoid shark Parotodus benedeni (le Hon) from the Yorktown Formation (Early Pliocene) at Lee Creek Mine, North Carolina. Mosasaur 6: 1-10.
  • Kent, B. W. 1998. Speculations on the size and morphology of the extinct lamnoid shark,Parotodus benedeni (le Hon). Mosasaur 6: 11- 15.
  • Kent, B. W. 1999. Part 2 - Sharks from the Fisher/Sullivan Site. In: R. E. Weems (ed.). Fossil Vertebrates and Plants from the Fisher/Sullivan Site (Stafford County): A Record of Early Eocene Life in Virginia. Virginia Division of Mineral Resources, Publ. 152, pp. 11-37.
  • Kent, B. W. 1999. Part 3 - Rays from the Fisher/Sullivan Site. In: R. E. Weems (ed.). Fossil Vertebrates and Plants from the Fisher/Sullivan Site (Stafford County): A Record of Early Eocene Life in Virginia. Virginia Division of Mineral Resources, Publ. 152, pp. 39-51.
  • Marbach-Ad, G. P. A. Shields, B. W. Kent, B. Higgins, K. V. Thompson. 2010. Team teaching of a prep course for graduate teaching assistants. Journal of Graduate Teaching Assistant Development, 13: 44-58.
  • Kent. B. W. (in prep.) The cartilaginous fishes (chimeroids, sharks, and rays) of Calvert Cliffs. In: S. Godfrey (ed.), The geology and vertebrate paleontology of Calvert Cliffs (Chesapeake Group), Maryland. University of Illinois Press.  

Awards

  • UMCP College of Life Sciences Faculty Excellence Award for Teaching/Advising, 1993
  • UMCP Presidential Award for Outstanding Service to the Schools, 1994
  • UMCP Outstanding Faculty Author, October, 1994
  • Maryland Governor's Citation, 1995
  • American Fossil Federation Certificate of Appreciation, 1995
  • American Fossil Federation Lifetime Appreciation Award, 1999
  • UMCP Certificate of Appreciation Award, 2004

Education

  • Oregon State University, B.S., magna cum laude, 1973
  • Oregon State University, M.S., 1976
  • University of Maryland, Ph.D., 1981