Monolophosaurus

Monolophosaurus was a predatory theropod dinosaur from the Middle to Late Jurassic of northwestern China. Known from an almost complete skull and articulated skeleton discovered in the Junggar Basin, it reached between five and five and a half metres in length. Its most defining characteristic was a prominent, narrow crest running down the centre of its snout from the nostrils to between the eyes. Because this bony structure was hollow and delicate, it was probably a visual ornament to attract mates or signal social rank, rather than a weapon for head-butting rivals. Monolophosaurus occupied a mid-tier predatory niche in its environment, coexisting with larger carnivores such as Sinraptor. Armed with curved teeth and sharp claws, it likely hunted juvenile sauropods, early horned dinosaurs, and primitive stegosaurs inhabiting the Jurassic river systems.

A hollow, delicate midline crest ran along three-quarters of its snout, likely used for display rather than combat.

Where and when

Monolophosaurus lived in the Middle Jurassic, from 165 to 161 million years ago (Callovian-Oxfordian age). Its remains come from China, in the Shishugou Formation.

The numbers

Length 5.4 m (estimates run from 5 to 5.7 m). Mass about 560 kg. Hip height about 1.7 m. That is 3.2 human-lengths, or 0.48 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

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