Hatchling (Dinotopia) by Midori Snyder

Janet, a young Hatchery apprentice, runs away when she accidentally endangers a dinosaur egg.  Then she meets a gravely wounded Gryposaurus, a very rare dinosaur.  Entrusted with the dying Gryposaurus's newly laid egg, Janet knows she must brave the wilds of Dinotopia--and return to an uncertain reception at the Hatchery.