Stokesosaurus

Stokesosaurus was an early tyrannosauroid theropod that inhabited North America during the Late Jurassic period, roughly 150 million years ago. Its fossils were unearthed in the Cleveland-Lloyd Dinosaur Quarry in Utah. Known principally from pelvic elements, including distinctive ilia with prominent vertical ridges, Stokesosaurus demonstrates that the lineage leading to Tyrannosaurus rex began as relatively small, nimble hunters. It measured about three to four metres long and possessed a slender build suited for rapid pursuit of modest prey. Living in the shadow of gigantic predators like Allosaurus, Stokesosaurus occupied a mesopredator niche in the Morrison ecosystem.

It is one of the earliest known tyrannosauroids, identified from distinctive hip bones.

Where and when

Stokesosaurus lived in the Late Jurassic, from 155 to 148 million years ago (Kimmeridgian-Tithonian age). Its remains come from United States, in the Morrison Formation.

The numbers

Length 3.5 m (estimates run from 3 to 4 m). Mass about 95 kg. Hip height about 1.2 m. That is 2.1 human-lengths, or 0.31 of a double-decker bus. These are estimates from fragmentary remains; fields marked estimated by the site are length, mass, hip height.

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