Iguanodon was one of the first dinosaurs ever scientifically described, making it a landmark animal in the history of paleontology. Its name means iguana tooth because its leaf-shaped teeth reminded early scientists of modern iguanas. This dinosaur lived during the Early Cretaceous Period, about 126 to 122 million years ago, and is best known from Europe.
Studying Iguanodon helps scientists understand how large plant-eating dinosaurs moved, fed, and evolved.
Key Facts
- Name meaning: Iguanodon means iguana tooth.
- Time period: Iguanodon lived about 126 to 122 million years ago during the Early Cretaceous.
- Estimated length: adult Iguanodon reached about 8 to 10 m long.
- Estimated mass: many adults weighed about 3,000 to 5,000 kg.
- Body plan: Iguanodon could likely move on four limbs for walking and on two limbs for faster movement.
- Speed formula for estimates: speed = distance / time.
Vocabulary
- Ornithopod
- An ornithopod is a group of mostly plant-eating dinosaurs that often had strong hind legs and beaked mouths.
- Thumb spike
- A thumb spike is the pointed bone on Iguanodon's hand that may have been used for defense, feeding, or social behavior.
- Cretaceous Period
- The Cretaceous Period was a span of geologic time from about 145 to 66 million years ago when many dinosaur groups diversified.
- Fossil
- A fossil is preserved evidence of ancient life, such as a bone, tooth, footprint, or plant impression.
- Herbivore
- A herbivore is an animal that eats plants as its main food source.
Common Mistakes to Avoid
- Drawing the thumb spike as a nose horn is wrong because early reconstructions placed it on the snout before scientists realized it belonged on the hand.
- Calling Iguanodon a carnivore is wrong because its beak and grinding teeth show adaptations for eating plants.
- Assuming Iguanodon always walked upright is wrong because its skeleton suggests it could use both four-limbed walking and two-limbed movement.
- Treating every Iguanodon fossil as the same species is wrong because paleontologists have revised old classifications as better fossils and evidence became available.
Practice Questions
- 1 An Iguanodon is estimated to be 9 m long. If a human student is 1.5 m tall, how many student heights equal the dinosaur's length?
- 2 A herd of Iguanodon travels 600 m in 5 minutes. What is the herd's average speed in meters per minute?
- 3 Explain how the beaked mouth, leaf-shaped teeth, strong hind legs, sturdy tail, and thumb spikes each give clues about how Iguanodon lived.