Proceratosaurus

Proceratosaurus was a small predatory dinosaur known from a single fossil skull discovered in Gloucestershire, England, dating back to the Middle Jurassic around 167 million years ago. It was originally named under the assumption that it was an evolutionary forerunner of Ceratosaurus, due to a distinct nasal horn-core or crest on its snout. Modern phylogenetic studies, however, revealed that it is actually one of the earliest recognised members of the tyrannosauroid lineage. Measuring around three metres in length, it was an agile, two-legged carnivore that likely weighed less than a large human. Its slender jaws held numerous small, sharp teeth ideal for catching lizards, early mammals, and small ornithischian dinosaurs. Proceratosaurus demonstrates that the lineage leading to giant predators like Tyrannosaurus began as diminutive, crested hunters adorned in plumage.

Originally thought to be an ancestor of Ceratosaurus, modern analysis revealed it as the earliest known tyrannosauroid.

Where and when

Proceratosaurus lived in the Middle Jurassic, from 168 to 166 million years ago (Bathonian age). Its remains come from United Kingdom, in the White Limestone Formation.

The numbers

Length 3 m (estimates run from 2.8 to 3.2 m). Mass about 71 kg. Hip height about 1 m. That is 1.8 human-lengths, or 0.27 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

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