Dinosaurs / Cretaceous / Tenontosaurus
Tenontosaurus
Cretaceous teh-NON-toe-SAWR-us, “sinew lizard”
Tenontosaurus was a medium-to-large basal iguanodontian that lived in western North America during the Early Cretaceous, around 115 to 100 million years ago. Measuring up to seven metres in length and weighing around one tonne, it was roughly the bulk of an ox. Its most distinctive anatomical feature was an immensely long, deep tail stiffened by numerous criss-crossing bony tendons, giving rise to its generic name. It could walk on all four limbs when feeding on ground plants but could rise onto its hind legs to browse or run. Tenontosaurus fossils are frequently found closely associated with teeth and skeletons of the dromaeosaurid predator Deinonychus, indicating a recurring predator-prey dynamic.
Its exceptionally deep and long tail was heavily reinforced by a network of ossified tendons.
Where and when
Tenontosaurus lived in the Early Cretaceous, from 115 to 100 million years ago (Aptian-Albian age). Its remains come from United States, in the Cloverly Formation.
The numbers
Length 6.5 m (estimates run from 6 to 7 m). Mass about 980 kg. Hip height about 1.8 m. That is 3.8 human-lengths, or 0.58 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.