Dinosaurs · Large ornithopod

Tenontosaurus

Say it ten-ON-toe-sore-us. The name means ‘sinew lizard’.

Tenontosaurus beside a person 1.75 m tall. Ticks mark every metre.Body shape drawn for this site, showing the general build of large ornithopods

Length: 7 m
Weight: 900 kg
Diet: Plant-eaterplant material
Walked: On 4 legs
When: Early Cretaceous120 to 110 million years ago
Fossils found in: Canada, USA
Named by: Ostrom (1970)
Family tree: Dinosauria › Ornithischia › Ornithopoda › Euornithopoda › Iguanadontia

Where Tenontosaurus sits in the age of dinosaurs.Periods from the ICS chart; dinosaur dates from the Natural History Museum

Large ornithopods. Big plant-eaters that walked on two or four legs, including the duck-billed dinosaurs. See all 36

Lived at the same time

Sauropelta · same country
Zephyrosaurus · same country
Silvisaurus · same country
Acrocanthosaurus · same country
Deinonychus · same country
Nodosaurus · same country
Archaeoceratops
Atlascopcosaurus

Other large ornithopods

Fukuisaurus Early Cretaceous
Lurdusaurus Early Cretaceous
Probactrosaurus Early Cretaceous
Ouranosaurus Early Cretaceous
Equijubus Early Cretaceous
Jinzhousaurus Early Cretaceous
Muttaburrasaurus Early Cretaceous
Iguanodon Early Cretaceous

Source: Tenontosaurus in the Natural History Museum Dino Directory, read 12 November 2026. Sizes are the museum's estimates for a typical adult. "Lived at the same time" lists dinosaurs whose dates overlap, which does not always mean they met.