Tenontosaurus Characteristics

Tenontosaurus measured 26 feet (8 metres) in length, 10 feet (3 metres) in height (in bipedal stance) and weighed around 2 tons. It was large and heavily built and quadrupedal/bipedal but spent most of its time on 4 legs, grazing but could also rear up onto its hind legs to forage in trees. Tenontosaurus had a long, broad tail which was stiffened by a network of bony tendons. Most of the tendons on ornithopod dinosaurs are strong along their backbone and hip regions. Tenontosaurus had a beak similar to other bird-footed dinosaurs.

Tenontosaurus was a herbivore and its diet would have consisted of ferns, cycads, gingkos and primitive flowering plants. Its powerful, U-shaped beak and the angled cutting surfaces of its teeth meant it was not limited to which part of the plant it consumed. Leaves, wood and even fruit may have formed part of its diet.

Tenontosaurus was most probably preyed up on by packs of carnivorous Deinonychus. Tenontosaurus specimens have been found at over 50 sites, and 14 of those also contain Deinonychus remains. It is likely that Deinonychus favoured juvenile Tenontosaurus, and that when Tenontosaurus reached a certain size, it passed out of range as a food source for the small theropods, though they may have scavenged larger individuals.

The first Tenontosaurus fossil was found in Big Horn County, Montana by an American Museum of Natural History expedition in 1903. Subsequent digs in the same area during the 1930s unearthed 18 more specimens, and 4 specimens were found during the 1940s. Since 1970, many more Tenotnosaurus specimens have been reported.

There are 2 species, Tenontosaurus tilletti, described by John Ostrom in 1970 and Tenontosaurus dossi, described by Winkler, Murray, and Jacobs in 1997.