Héctor E. Rivera-Sylva is a paleontologist with the Museo del Desierto in Saltillo, Coahilla, Mexico. Kenneth Carpenter is Associate Vice-Chancellor, Prehistoric Museum, the College of Eastern Utah. He is author of Eggs, Nests, and Baby Dinosaurs (IUP, 2000); editor of The Carnivorous Dinosaurs (IUP, 2005) and The Armored Dinosaurs (IUP, 2000); and editor (with Peter Larson) of Tyrannosaurus rex, the Tyrant King (IUP, 2008), (with Virginia Tidwell) of Thunder-Lizards: The Sauropodomorph Dinosaurs (IUP, 2005), and (with Darren H. Tanke) of Mesozoic Vertebrate Life (IUP, 2001). Eberhard Frey is Chief Curator and Head of the Department of Geosciences at State Museum of Natural History Karlsruhe, Germany.