Stenonychosaurus

Stenonychosaurus was a small, agile troodontid theropod that roamed North America during the Late Cretaceous period, around 76 million years ago. Measuring roughly two to two and a half metres long and weighing about forty kilograms, it was comparable in size to a slender wolf. It walked upright on two long hind legs, equipped with an enlarged, sickle-shaped claw on the second toe of each foot. Its large forward-facing orbits indicate excellent stereoscopic vision, suggesting it was well suited to hunting in low light or at twilight. Stenonychosaurus had small serrated teeth suitable for capturing insects, small mammals, and reptiles, or possibly consuming eggs and fruit. For several decades its fossils were lumped under the name Troodon, but recent anatomical reassessments have reinstated Stenonychosaurus as a valid, distinct genus.

It possessed extraordinarily large eye sockets and a high encephalisation quotient relative to other Mesozoic dinosaurs.

Where and when

Stenonychosaurus lived in the Late Cretaceous, from 76.5 to 75 million years ago (Campanian age). Its remains come from Canada, in the Dinosaur Park Formation.

The numbers

Length 2.3 m (estimates run from 2 to 2.5 m). Mass about 42 kg. Hip height about 0.9 m. That is 1.4 human-lengths, or 0.21 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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