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.