Payne, Jonathan L., Boyer, Alison G., Brown, James H., Finnegan, Seth, Kowalewski, Michal, Krause, Richard A., Lyons, Sara K., McClain, Craig R., McShea, Daniel W., Novack-Gottshall, Philip M., Smith, Felisa A., Stempien, Jennifer A., and Wang, Steve C. 2009. "
Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity."
Proceedings of the National Academy of Sciences of the United States of America. 106 (1):24–27.