Altirhinus

Altirhinus was an advanced herbivorous iguanodontian dinosaur that lived in the semi-arid environments of Early Cretaceous Mongolia. It is immediately recognised by the pronounced tall arch formed by its nasal bones, which gave the snout a prominent arched profile. This structure may have supported a soft-tissue resonating chamber used for vocal communication, visual species recognition, or heat exchange. Reaching up to eight metres in length, Altirhinus possessed robust front limbs with broad hand claws, alongside a small, pointed thumb spike inherited from its basal iguanodontian ancestors. It fed primarily on tough shrubs and low branches, using its cropping beak and batteries of self-sharpening teeth to process coarse vegetation. The fossil remains, including well-preserved skulls and limbs of adult and juvenile individuals, demonstrate that this animal was a key component of Mongolia's diverse mid-Cretaceous terrestrial ecosystems.

Its nasal bones arched dramatically upwards, forming a distinctive tall crest across the bridge of its snout.

Where and when

Altirhinus lived in the Early Cretaceous, from 113 to 100.5 million years ago (Aptian-Albian age). Its remains come from Mongolia, in the Khukhtek Formation.

The numbers

Length 7.3 m (estimates run from 6.5 to 8 m). Mass about 2.1 t. Hip height about 2.2 m. That is 4.3 human-lengths, or 0.65 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

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