Bactrosaurus

Bactrosaurus was a medium-sized early hadrosauroid that lived in the Cretaceous floodplains of what is now Inner Mongolia, China. Adults grew to around six metres long and weighed somewhere between one and two tonnes. Anatomically, Bactrosaurus represents an evolutionary transition between early iguanodontians and the true duck-billed dinosaurs. It possessed dental batteries adapted for grinding abrasive plant material, yet retained primitive traits such as three teeth per socket and a flat, crestless skull. It had club-shaped tips on the neural spines of its backbone, which inspired its scientific name. Bactrosaurus could move on all fours while feeding on low vegetation, but had sturdy hind legs capable of supporting a bipedal stance while walking briskly or running from predators.

Its dorsal vertebrae have unusually swollen, club-like tips on their neural spines.

Where and when

Bactrosaurus lived in the Late Cretaceous, from 96 to 85 million years ago (Cenomanian-Santonian age). Its remains come from China, in the Iren Dabasu Formation.

The numbers

Length 5.3 m (estimates run from 4.5 to 6 m). Mass about 1.5 t. Hip height about 2 m. That is 3.1 human-lengths, or 0.47 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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