Iguanodon fossils are some of the first dinosaur bones ever found. A tooth and a few bones were found by a British scientist named Gideon Mantell in the 1820s. These first fossils looked like the teeth of a modern iguana. That is how Iguanodon got its name, which means “iguana tooth”. This is what Mantell thought the Iguanodon looked like. Along with the bones, a large spike was found. They thought it grew out of Iguanodon’s nose, like a modern iguana. But today we know that it was actually a thumb claw used to defend itself. It was about six inches long.
Iguanodon lived about 135 to 125 million years ago. The Iguanodon was a very successful dinosaur; the species survived for a long time. Iguanodon bones have been found in many places. Even though Pangea, the large land mass, was breaking apart, Iguanodon spread and lived in every continent except Antarctica. Iguanodon was a big herbivore, meaning that it ate only plants. It grew to be about 30 feet long and 16 feet tall. That is about the size of a school bus. It might have weighed four to five tons. Iguanodon had thick, powerful back legs. Its front legs were thinner and lighter. It spent most of its time on all fours, but could run on two legs when it needed to move quickly. It was a relatively fast dinosaur. We know this by studying the dinosaur’s trackways or footprints. It could rear up onto its two back legs in order to escape from predators, and it could use its hands to gather food.
Iguanodon had a flat, stiff tail, which stuck straight out behind it for balance. It had no front teeth - just a horn-covered beak which it used to rip the leaves off cycads or other tough plants. In the back of its mouth it had rows of grinding teeth packed closely together. Its teeth were about two inches long. It ground up the plants with its powerful back teeth. Iguanodon may have been one of the first dinosaurs that could chew its food. Its upper jaw could move from side to side. Paleontologists believe that Iguanodon traveled in large groups. We know this because about 30 Iguanodon skeletons were found together in a coal mine in Belgium, in Northern Europe. Among them were bones of adults and younger dinosaurs. Hundreds of Iguanodon fossils have been found around the world. Skeletons, footprints and eggs have mostly been found in Belgium, England, Germany, North Africa and North America.