About the Authors

Bruce S. Lieberman

To whom correspondence should be addressed. E-mail: blieber@ku.edu

Affiliation Department of Geology and Natural History Museum, University of Kansas, Lawrence, Kansas, United States of America

Adrian L. Melott

Affiliation Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: BL. Analyzed the data: AM. Wrote the paper: BL AM.