Christopher B.T. Waid. Department of Earth and Environmental Sciences, University of Iowa, 115 Trowbridge Hall, Iowa City, IA 52242, USA; Present address: Ohio Geological Survey, 2045 Morse Rd. Building C, Columbus, OH 43229, USA. christopher.waid@dnr.ohio.gov

Chris Waid recently received a M.S. in Geoscience from the University of Iowa, and received his B.A. in Geological Sciences from SUNY Geneseo. He is interested in any aspect of geology related to Earth History, and has focused on conodont biostratigraphy and taxonomy, lithostratigraphy, and chemostratigraphy throughout his undergraduate and graduate education. He is currently a geologist at the Ohio Geological Survey, where he works on high-resolution subsurface stratigraphy in the Energy Resources Group.

Bradley D. Cramer. Department of Earth and Environmental Sciences, University of Iowa, 115 Trowbridge Hall, Iowa City, IA 52242, USA. bradley-cramer@uiowa.edu

Brad Cramer is an Earth-systems scientist with a background in stratigraphy and isotope geochemistry. He investigates global change events in deep time with an emphasis on Pre-Mesozoic stratigraphy. His work integrates biostratigraphy, stable and radiogenic isotope chemostratigraphy, sequence stratigraphy, and high-precision geochronometry to develop high-resolution/high-precision time scales of Earth history and to evaluate the cause-and-effect relationships within the Earth system. He specializes in lower Paleozoic Earth history but has worked on topics ranging from the Proterozoic to the Permian in basins around the world. He is also the director of the University of Iowa MicroPaleontology Laboratory (http://bradley-cramer.weebly.com/micropaleo-lab.html).