Mark Hallett is a naturalist, scientific artist, and author who specializes in prehistoric animals and their environments. His art and writing have appeared in Life, Smithsonian, and National Geographic. He is coauthor of Seismosaurus: The Earth Shaker (Columbia, 1994) and The Sauropod Dinosaurs: Life in the Age of Giants (2016), among other works.

John M. Harris is chief curator emeritus at the Natural History Museum of Los Angeles County and visiting associate in geology at the California Institute of Technology. He is coeditor of Laetoli: A Pliocene Site in Tanzania (1987) and Lothagam: The Dawn of Humanity in Eastern Africa (Columbia, 2013).