Mesozoic Era Early Cretaceous Period Dinosaurs Iguanodon


Quick Facts
Name Meaning:Iguana Tooth
Distribution:Western USA; Western Europe; Romania; Mongolia
Time Period:Early Cretaceous, 125 Ma
Length:30 ft. (9 m)
Weight:7 tons
Linnaean Classification
Cladistic Classification
  • Dinosauria
    • Ornithischia
      • Genasauria
        • Cerapoda
          • Ornithopoda
            • Euornithopoda
              • Iguanodontia
                • Dryomorpha
                  • Ankylopollexia
                    • Styracosterna
                      • Iguanodontoidea
                        • Iguanodontidae
                          • Iguanodon


The Iguanodon was first discovered in 1822 and described in 1825 by Gideon Mantell, an English geologist. It was the second dinosaur formally named, after the Megalosaurus. It is part of a diverse and populous group of dinosaurs resulting in many species mistakenly intermingled and reassigned to other groups. Thanks to this diversity a lot is known about the Iguanodon and its family. It has been found in almost all the continents including Europe, Asia, Africa, and North America. It was named after its teeth which are shaped and have a function similar to the teeth of modern Iguanas, but much bigger. At first the Iguanodon was thought to be a horned dinosaur like the Rhinoceros. This horn was later discovered as a spike located on the animal's thumb. It, like the Tyrannosaurus, was mistakenly thought to walk upright with the tail dragging along the ground. In the 1970's it was found that this was not the case as the stiff tail would have broken with the strain put on it.


The Iguanodon was a large and heavy dinosaur. It had high-ridged cheek teeth like the iguana lizard, located within a large beak with a strong tongue. It also probably had something similar to a cheek in order to keep food in its mouth. It had very stiff tendons in parts of its body that would eventually turn to bone as the dinosaur matured, making its tail and certain other areas very stiff. It legs were strong but not well built for running. The distinguishing feature of the Iguanodon was its claw found on its five-fingered hand. This claw was probably used for defense against predators. The hand also had a grasping fifth finger.


The Iguanodon could walk on two legs or four, similar to others of its kind. It probably walked more on two legs, with the front legs coming in handy when needing to bend over to eat or drink. Tracks, attributed to the Iguanodon, are usually found with just imprints of the back legs. As certain tendons hardened to bone it may have found it easier to walk on four legs as it aged. The animals teeth would have allowed it to feast on tougher plant materials. It could have run, though not too fast, and when cornered it could have used its thumb spike as a defense. The thumb could also have been used to forge for food with its hand's unique grasping ability. It probably traveled in herds, with evidence found in Germany of several fossils found together.

ScienceViews Writer: Jason Hamilton.

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