Lythronax

Lythronax was an early tyrannosaurid that prowled the ancient island continent of Laramidia, in what is now southern Utah, roughly 80 million years ago. Measuring around eight metres in length and weighing over two tonnes, it was the apex carnivore of its coastal floodplain ecosystem. What makes Lythronax especially significant is the shape of its skull: the back of the skull was wide while the snout was relatively narrow. This arrangement placed the eyes facing forward, granting it stereoscopic vision and superior depth perception much like Tyrannosaurus rex, but millions of years earlier. Armed with thick, robust teeth capable of puncturing flesh and cracking bone, it hunted duck-billed dinosaurs and horned dinosaurs. Its discovery demonstrated that advanced tyrannosaurid physical traits evolved much earlier and more southerly than scientists had previously supposed.

Its skull broadened at the back, giving it forward-facing eyes and stereoscopic binocular vision earlier than any known relative.

Where and when

Lythronax lived in the Late Cretaceous, from 80.6 to 79.9 million years ago (Campanian age). Its remains come from United States, in the Wahweap Formation.

The numbers

Length 7.7 m (estimates run from 7.3 to 8 m). Mass about 1.9 t. Hip height about 2.2 m. That is 4.5 human-lengths, or 0.69 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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