Ceratosaurus

Ceratosaurus is a genus of carnivorous theropod dinosaurs that lived during the Late Jurassic period, roughly 153 to 148 million years ago. Fossils have been found primarily in North America, with the best-known remains coming from the Morrison Formation and surrounding sediments. The genus is most closely associated with a single well-supported species, Ceratosaurus nasicornis, though several other species have been named in the past and are generally considered dubious.

Physically, Ceratosaurus was a mid-sized theropod with a long skull and a distinctive horn or horn-like projection on the nasal region. Its skull bore sharp, recurved teeth suited to slicing flesh. The forelimbs were relatively short with three fingers, while the hind limbs were long and powerful, adapted for bipedal locomotion. Estimates for adult length range around approximately 5 to 7 meters (16 to 23 feet), with body mass in the low hundreds of kilograms to around a metric ton in larger reconstructions.

Discovery and classification: Ceratosaurus was named by Othniel Charles Marsh in 1884. The name means “horned lizard.” It is placed within the clade Ceratosauria and is commonly assigned to the family Ceratosauridae, one of the early-diverging lineages of theropod dinosaurs.

Paleobiology and ecology: Ceratosaurus was likely an active predator that may have pursued diverse prey, including smaller dinosaurs and possibly medium-sized vertebrates. Its facial helmet and dentition suggest a feeding strategy focused on flesh-tearing bites. It coexisted with other theropods, large sauropods, and armored dinosaurs within the Morrison ecosystem, indicating niche differentiation among carnivores of its time.