Thomas R Holtz

DR. THOMAS R. HOLTZ, JR. (self-proclaimed "King of the Dino Geeks") is one of the world's leading experts on tyrannosaurs. He is the Faculty Director of the Science & Global Change Program at the University of Maryland in College Park, and a Research Associate in the Department of Paleobiology, Nation Museum of Natural History, Smithsonian Institution. He maintains a Web site of chapter updates to Dinosaurs at geol.umd.edu/ tholtz/dinoappendix. You can also follow him on Twitter @tomholtzpaleo.

LUIS V. REY is the winner of the 2008 Lazendorf PaleoArt Award--the most prestigious international award recognizing achievement in paleontological scientific illustration. He lives in London, England. You can follow his blog at luisvrey.wordpress.com.