Staff and Scientist Biographies

Kirk Johnson, PhD

Vice President of Research & Collections and Chief Curator, Denver Museum of Nature & Science
Dr. Johnson joined the Museum in 1991 after earning his doctorate in geology and paleobotany from Yale University. He studies fossil plants, terrestrial stratigraphy, geochronology, and dinosaur extinction and has published many popular and scientific books and articles. He is best known for his research on fossil plants, which is widely accepted as some of the most convincing support for the theory that an asteroid impact caused the extinction of the dinosaurs. His research has taken him to Alaska's Bering Sea, the Brazilian Amazon, the Canadian High Arctic, the rainforests of New Zealand, the Gobi desert, India, China, Patagonia, and the American West. His book, "Cruisin' the Fossil Freeway," won the Colorado Humanities award for best nonfiction book in 2007.

Ian Miller, PhD

Chair, Department of Earth Sciences, Curator of Paleontology, Denver Museum of Nature & Science
Dr. Miller received his PhD in geology and geophysics from Yale University in 2007. Dr. Miller studies fossil plants, paleoclimate, paleoecology, and tectonics. Dr. Miller's current research projects include the uplift history of the Colorado Front Range; the displacement of geologic terranes on the west coast of North America; Cretaceous-Tertiary plant diversity in the Denver Basin; the taxonomy of Late Jurassic through Eocene floras in the American West; and the fossil plants of the Grand Staircase Escalante National Monument.

Steve Holen, PhD

Curator of Archaeology, Denver Museum of Nature & Science
Dr. Holen joined the Museum in 2001 after completing his doctorate in anthropology at the University of Kansas. Dr. Holen has more than 30 years of experience in Great Plains archaeology and extensive experience with public education in a museum setting.

His research has focused on the Clovis people-the earliest well-known North American human culture at 13,000 years old. He has studied Clovis use and long-distance movement of stone tools in the central Great Plains of North America. He has also excavated several pre-Clovis mammoth sites that date between 16,000 and 20,000 years old. These sites are significant because they reveal evidence that humans were in North America long before the Clovis people. This is one of the most hotly debated topics in North American archaeology.

George Sparks

President & CEO, Denver Museum of Nature & Science
George Sparks, President & CEO since November 2004, received a master's degree in aeronautics and astronautics from MIT, and a bachelor's degree in aeronautical engineering from the United States Air Force Academy. Sparks served as an Air Force pilot and was an assistant professor of aeronautics at the United States Air Force Academy. From 1979 to 1999, he worked for Hewlett-Packard. From 1999 to 2003, he was a vice president for Agilent Technologies. Sparks has worked closely with Denver Public Schools and has served as a board member for many Colorado organizations, including the University of Colorado President's Leadership Class, Colorado MESA, Colorado Forum, the Public Education and Business Coalition, Colorado Bright Beginnings, and the Colorado Advisory Council of the Trust for Public Lands. He also serves on Mayor John Hickenlooper's Early Childhood Education Leadership Team.

Daniel Fisher, PhD

Professor of Ecology and Evolutionary Biology and Claude W. Hibbard Collegiate Professor of Paleontology, University of Michigan
Dr. Fisher completed his PhD in Geological Sciences at Harvard University in 1975. In 1979, he moved to the University of Michigan. Shortly after arriving in Ann Arbor, Fisher was called to several local sites where remains of mastodons had turned up during excavation of farm ponds. He is widely recognized as one of the world's leading mastodon experts. He has recently expanded his research to include woolly mammoths in northern Siberia. Dr. Fisher is the guest curator for a large, traveling exhibit called "Mammoths and Mastodons: Titans of the Ice Age," which opened March 5, 2010 at The Field Museum in Chicago.


About the Denver Museum of Nature & Science The Denver Museum of Nature & Science is the Rocky Mountain Region's leading resource for informal science education. A variety of engaging exhibits, discussions and activities help Museum visitors celebrate and understand the natural wonders of Colorado, Earth and the universe. The Museum is located at 2001 Colorado Blvd., Denver, CO, 80205.  To learn more about the Museum, check, or call 303-370-6000.

Many of the Museum's educational programs and exhibits are made possible in part by generous funding from the citizens of the seven-county metro area through the Scientific & Cultural Facilities District.

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