Tenontosaurus
Tenontosaurus was a big plant-eating dinosaur with a very long, stiff tail. It lived in North America during the Early Cretaceous period, about 115 to 108 million years ago.1
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Fun facts
Tenontosaurus had an unusually long and broad tail, stiffened by a network of bony tendons, which is why it is called 'sinew lizard'.1
An adult Tenontosaurus could reach a browsing height of about 3 meters (10 feet) if it stood on its hind legs, but it usually walked on all fours.1
Its beak was U-shaped and thick, and its lower jaw had a special bone called a predentary that helped form the lower beak.1
Tenontosaurus lived alongside the predator Deinonychus, and fossils of both are common in the same rocks.1
The first Tenontosaurus fossil was found in 1903 in Montana, but it was not named until 1970.1
There are two species: Tenontosaurus tilletti and Tenontosaurus dossi. T. dossi is known from only a few specimens in Texas.1
Most asked questions about Tenontosaurus
?How big was Tenontosaurus?
About 6 to 8 metres long and around 1,000 kilograms, though estimates vary by species and study.12
?What did Tenontosaurus eat?
It was a plant-eater. It used its U-shaped beak and chopping teeth to eat leaves, wood, fruit, and low-growing ferns and shrubs.12
?Did Tenontosaurus walk on two legs or four?
It usually walked on all four legs, but could stand on its hind legs to reach higher plants, up to about 3 metres.12
?Was Tenontosaurus bigger than Deinonychus?
Yes, adult Tenontosaurus were much larger than adult Deinonychus. Deinonychus probably hunted young or sick Tenontosaurus.1
?When did Tenontosaurus live?
It lived during the Early Cretaceous period, about 115 to 108 million years ago, in western North America.12
?Why did Tenontosaurus have a long tail?
Its tail was unusually long and broad, stiffened by bony tendons. This helped support the tail, but scientists aren't sure of its exact purpose.1
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Myth buster
Myth: Some people think Tenontosaurus was a slow, clumsy dinosaur.
Truth: Scientists think it was a common and successful herbivore, and its stiff tail may have helped it balance.1
For dino experts
- Scientific name
- Tenontosaurus
- Named by
- Ostrom 19703
- Group
- Beaked plant-eaters
- Family / clade
- Tenontosauridae3
- Classification
- Ornithischia > Ornithopoda > Iguanodontia3
- Age of the rocks
- 121 to 94 million years (Aptian / Cenomanian)3
- Rock formations
- Cloverly, Antlers, Cedar Mountain3
- Countries
- USA3
- Fossil records
- 83 in the Paleobiology Database3
- Discovery
- The first fossil was found in 1903 by an American Museum of Natural History expedition in Montana. John Ostrom named it Tenontosaurus tilletti in 1970 after studying many specimens.1
- Still debated
- Scientists still debate exactly how Tenontosaurus moved, whether it was mostly quadrupedal or could run on two legs.1
Where the facts come from
- Tenontosaurus (en.wikipedia.org)
- Tenontosaurus | Natural History Museum (nhm.ac.uk)
- Tenontosaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.
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Giganotosaurus
Microraptor
Deinonychus
Baryonyx