Tenontosaurus was a bulky, powerful herbivore that weighed about the same as a large car and was about the same size as a double-decker bus. It had long, powerful limbs and a parrot-like beaked mouth.
Judging by the number of remains that have been found, including 25 skeletons and scattered bones and teeth, Tenontosaurus must have been one of the most abundant herbivores in early Cretaceous North America. It was certainly attractive to carnivores – one skeleton has been found surrounded by the bodies of several Deinonychus that had been killed while attacking it.
Name: Tenontosaurus, meaning ‘tendon lizard’
Size: 6.5m long
Lived: 110 million years ago in the Middle Cretaceous Period in North America
Tenontosaurus is like a hypsilophodontid but lacks the teeth on the front part of its jaw. Otherwise it is like an iguanodontid, but the classification is still not clear. Its distinctive feature is its very long tail – longer than the rest of the body – and the network of tendons that support the spine. Its long forelimbs and strong finger bones suggest that it walked on all fours for most of the time.
A bulky dinosaur, Tenontosaurus could walk on all fours or pick its way across the landscape on its hind legs. At the end of its front limbs were stocky hands with five fingers on each. Tenontosaurus balanced on the four long toes on each back foot when it stretched into the treetops for a mouthful of leaves or twigs. When it ran, it gripped the ground with its toes, and raised its long, wide tail to balance the weight of its heavy chest and bulging stomach.
Tenontosaurus’ beak had no teeth, but it had ridged teeth running along the side of its beaked mouth. It used these to chew leaves it nipped off trees. When it was attacked, it would lash out with its tail.