Sonidosaurus

Sonidosaurus was a small titanosaurian sauropod that lived in what is now Inner Mongolia, China, during the Late Cretaceous. Described from a partial postcranial skeleton including vertebrae, pelvic bones, and parts of both hindlimbs, it is notable for its modest proportions. While many sauropods reached enormous body masses, Sonidosaurus measured only around nine metres in length and weighed roughly three tonnes. It inhabited floodplain environments alongside the giant oviraptorosaur Gigantoraptor, which was discovered in the same quarry. Its relatively lightweight build and slender limb proportions indicate a sauropod adapted to low-browsing across semi-arid river systems. Sonidosaurus provides important evidence that sauropods diversified into smaller ecological niches late in the Cretaceous, even in environments dominated by massive theropods and ornithopods.

It was unusually small for a titanosaur, measuring under ten metres in total body length.

Where and when

Sonidosaurus lived in the Late Cretaceous, from 85 to 72 million years ago (Santonian-Campanian age). Its remains come from China, in the Iren Dabasu Formation.

The numbers

Length 9 m (estimates run from 8 to 10 m). Mass about 3.2 t. Hip height about 2.2 m. That is 5.3 human-lengths, or 0.8 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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