Abrosaurus

Abrosaurus is a modest-sized sauropod known from the famous Dashanpu Quarry of Sichuan, China. Living during the Middle Jurassic period, this herbivore grew to roughly nine or ten metres long and weighed around four tonnes, making it fairly small compared to many of its giant relatives. It is best known for its pristine fossilised skull, which earned it the name delicate lizard due to its deeply arched, lightweight structure pierced by large cranial fenestrae. Its short, boxy head and spatulate teeth indicate that Abrosaurus specialised in biting through tough plant matter. Although sometimes aligned with the mamenchisaurids, its skull architecture strongly hints at close ties to basal macronarians like Camarasaurus.

Its skull was unusually boxy and delicate, perforated by exceptionally large openings separated by thin bone struts.

Where and when

Abrosaurus lived in the Middle Jurassic, from 168.3 to 163.5 million years ago (Bathonian-Callovian age). Its remains come from China, in the Lower Shaximiao Formation.

The numbers

Length 9.5 m (estimates run from 9 to 10 m). Mass about 3.9 t. Hip height about 2.2 m. That is 5.6 human-lengths, or 0.85 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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