Allosaurus fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans, several species of pterosaur, numerous dinosaur species, and early mammals such as docodonts, multituberculates, symmetrodonts, and triconodonts. Dinosaurs known from the Morrison include the theropods "Ceratosaurus", "Ornitholestes", "Tanycolagreus", and "Torvosaurus", the sauropods "Haplocanthosaurus", "Camarasaurus", "Cathetosaurus", "Brachiosaurus", "Suuwassea", "Apatosaurus", "Brontosaurus", "Barosaurus", "Diplodocus", "Supersaurus", and "Amphicoelias", and the ornithischians "Camptosaurus", "Dryosaurus", and "Stegosaurus". "Allosaurus" is commonly found at the same sites as "Apatosaurus", "Camarasaurus", "Diplodocus", and "Stegosaurus". The Late Jurassic formations of Portugal where "Allosaurus" is present are interpreted as having been similar to the Morrison but with a stronger marine influence.
Dinosaur egg and a system of classification based on the structure of eggshell was developed in China before gradually diffusing into the West. Dinosaur eggshell can be studied in thin section and viewed under a microscope. The interior of a dinosaur egg can be studied using CAT scans or by gradually dissolving away the shell with acid. Sometimes the egg preserves the remains of the developing embryo inside. The oldest known dinosaur eggs and embryos are from "Massospondylus", which lived during the Early Jurassic, about 190 million years ago. In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern