Ornithopsis

Ornithopsis is a historically significant Early Cretaceous sauropod from the Isle of Wight in southern England. When palaeontologist Harry Govier Seeley first examined its large, pneumatic back vertebrae, he was so struck by their internal cavities and light construction that he mistook the animal for a gigantic transitional flying reptile or bird. Later research clarified that these hollow chambers were actually adaptations seen in titanosauriform sauropods to lighten their massive frames. Although known primarily from isolated vertebrae and fragmentary remains from the Wessex Formation, Ornithopsis represents a substantial herbivore measuring fifteen to twenty metres in length. It inhabited a seasonal, subtropical river valley alongside dinosaurs such as Iguanodon, Neovenator, and Hypsilophodon, feeding on conifers and ferns.

Harry Seeley originally thought its deeply pocketed, pneumatic vertebrae belonged to an enormous bird or pterosaur.

Where and when

Ornithopsis lived in the Early Cretaceous, from 130 to 125 million years ago (Barremian age). Its remains come from United Kingdom, in the Wessex Formation.

The numbers

Length 18 m (estimates run from 15 to 20 m). Mass about 15 t. Hip height about 3.8 m. That is 10.3 human-lengths, or 1.56 of a double-decker bus. These are estimates from fragmentary remains; fields marked estimated by the site are length, mass, hip height.

Compare Ornithopsis with a bus Place on the timeline