Ceratosaurus

Chapter • Meet the dinosaur

Overview

Ceratosaurus nasicornis was a medium-sized predatory dinosaur with one of the most distinctive skulls of any theropod. A flattened, blade-like horn rose from the fused nasal bones, and a low bony ridge sat in front of each eye. The skull was deep but narrow, and it carried remarkably long, sabre-like teeth — proportionally among the longest of any Jurassic predator. The animal walked on two legs with the back held horizontally and a long, muscular tail as a counterbalance; the tail never dragged on the ground. That tail was unusually tall and flattened from side to side, and a row of small bony plates called osteoderms ran down the midline of the back, a rare feature among carnivorous dinosaurs. The hands bore four fingers rather than the three of Allosaurus. No evidence of feathers is known for ceratosaurs, so reconstructions show scaly skin with dorsal armour.

Chapter • Where it lived

Habitat

Ceratosaurus lived roughly 153–148 million years ago, in the closing stages of the Jurassic, on the broad river plains of what is now the American West. The holotype was collected in 1883–1884 by Marshall Felch at Garden Park near Cañon City, Colorado, and named by Othniel Charles Marsh in 1884. Additional material comes from the Morrison Formation in Utah and Wyoming, and very similar remains have been excavated from the Lourinhã Formation of Portugal. The setting was a seasonally dry lowland crossed by meandering rivers, with gallery forests of conifers and ferns and long droughts — a landscape shared with Allosaurus, Stegosaurus, Diplodocus and Camarasaurus.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy