Ceratosauridae

Ceratosauridae is a family of theropod dinosaurs within the larger clade Ceratosauria. The composition and limits of the group have varied among researchers; traditional schemes placed Ceratosaurus and several closely related genera in Ceratosauridae, while some modern analyses restrict Ceratosauridae to Ceratosaurus and a small set of near relatives, with other ceratosaurs assigned to Noasauridae or to broader ceratosaur groups. The exact membership remains debated in paleontological literature.

Fossil range and distribution are best documented for Late Jurassic rocks, particularly in North America. The most complete and well-known member is Ceratosaurus, from the Morrison Formation and similar deposits. Because remains from other continents are fragmentary or disputed, the geographic and temporal scope of Ceratosauridae is less well defined than for some other theropod groups.

Anatomy and ecology: Ceratosaurids were carnivorous, bipedal theropods. They generally show a combination of robust skulls and cranial ornamentation, with toothed jaws adapted to predation. Ceratosaurus, the type genus, is notable for features such as a tall snout region and distinctive cranial crests or bosses in some related forms. Across the group, skeletal material suggests a range of sizes and ecological niches, but all are interpreted as meat-eating predators of their ecosystems.

Discovery and naming: The genus Ceratosaurus means “horned lizard,” and it provides the basis for the family’s name. Ceratosaurus nasicornis is the best-known and most completely described member, anchoring the traditional concept of Ceratosauridae in the Late Jurassic of North America.