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Iguanodon, Early CretaceousWeald Clay Formation, United Kingdom · named 1825
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Iguanodon

ig-WAH-nuh-don

"iguana tooth"

Lived
143 to 120 million years ago, Early Cretaceous
Diet
Herbivore
Length
about 10 m (33 ft)
Group
Ornithopods
Found in
United Kingdom, Spain, Germany, France and Portugal
Named by
Mantell 1825

Size comparison

To scale

Where its fossils were found

The evidence

Today

107 finds

130 million years ago

Map: C. R. Scotese, PALEOMAP

Also reported from Belgium and China.

Habitat

Rivers, lakes and low floodplains covered parts of Early Cretaceous Europe, with ferns, horsetails and conifers. Regional neighbors included Mantellisaurus, Polacanthus and Baryonyx.

Field notes

About Iguanodon

A bulky, adaptable plant-eater

Iguanodon was a bulky plant-eater that could walk on two legs or drop onto all four, growing to roughly 10 meters, or about 33 feet, in length. It had a long, prehensile fifth finger for gathering food and a large, sharp thumb spike on each hand, likely used for defense. Its jaws held rows of ridged teeth for grinding tough plants, teeth that reminded early scientists of an iguana's, which is how the animal got its name.

Its world

Iguanodon lived during the Early Cretaceous, between about 143 and 120 million years ago, across what is now the United Kingdom, Spain, Germany, France, and Portugal, with additional finds reported from Belgium and China. Its remains have turned up in 107 separate finds, preserved in rock beds such as the Weald Clay and Wessex formations, making it one of the better-known dinosaurs of its time. It shared its world with the armored Polacanthus and Hylaeosaurus, the small Hypsilophodon, the sauropod Cetiosaurus, the clawed hunter Baryonyx, and its close relative Mantellisaurus.

How it was found

Mantell named Iguanodon in 1825, working from teeth and bone fragments found in the United Kingdom. It was only the second dinosaur genus ever formally named. Because later Iguanodon skeletons turned up more complete, scientists revised their picture of the animal more than once, moving it from an early reconstruction as a heavy, four-legged creature to the two-legged animal recognized today. Its relatives include Camptosaurus and the more recently named Bayannurosaurus, part of the wider group of plant-eaters called Iguanodontia.

Field gallery

More views of Iguanodon

Scenes reconstructed from the available fossil evidence.

Iguanodon in its habitat, photo 1

1 of 6

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Iguanodon.

The evidence

The science behind Iguanodon

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • Nearly complete adult skeletons show a bulky body, strong hindlegs and a long balancing tail.
  • Each hand has compact middle fingers for bearing weight, a separate thumb spike and an outer grasping finger.
  • The jaws carry rows of ridged teeth for processing plants behind a toothless beak.

Borrowed from relatives

  • Very little of the skeleton needs borrowing: nearly complete adults show almost the whole body.
  • A scaly covering follows comparisons with related plant eaters such as hadrosaurs.

Still unknown

  • Its color and the exact pattern of its scales.
  • The species identity and complete appearance of the reported young.
  • How its thumb spikes developed as it grew.

Often drawn wrong

  • The spike belongs on the thumb, rather than the nose or wrist.
  • Its long tail balanced the body above the ground, rather than propping it up like a kangaroo.
  • Its hands had specialized fingers, rather than mammal-like paws.

Discovery timeline

  1. 1825Named itMantell
  2. 1987Growing upNorman
  3. 2010Family treeNORMAN
  4. 2012Family treeMcDonald
  5. 2017Full descriptionVerdú et al.

Key papers

The research behind what we know of Iguanodon

Close relatives

Other members of Ankylopollexia

Sources: Wikidata