The authors are the curators responsible for the American Museum of Natural History's Hall of Dinosaurs. Mark Norell was co-leader of the American Museum of Natural History's Gobi Desert expeditions from 1992 to the present, in the course of which he discovered fossil remains of a new species of dinosaur as well as a unique dinosaur embryo. Eugene Gaffney is curator of Vertebrate Paleontology at the Museum. He is one of the world's leading specialists on fossil reptiles. Lowell Dingus is director of the Museum's Fossil Halls renovation. He served as head geologist on the Gobi Desert expeditions.