Iguanodon Characteristics

Iguanodon measured 20 - 36 feet (6 - 11 metres) in length, 16 feet (5 metres) in height and weighed an average of 5.5 tons. The most distinctive feature of this dinosaur is the large razor sharp 'thumb spike' which was perpendicular to the 3 main digits and probably used as a defence against predators or used to forage for food. Iguanodonts had bulky bodies and long, stiff, heavy tails. Iguanodon usually walked on 4 legs (quadrupedal) but could run on 2 legs (bipedal) which made them quite nimble despite their great size. They could move as fast as 20 kilometres per hour. This dinosaur had a large, tall but narrow skull, with a toothless beak probably covered with keratin, and teeth like those of an iguana, but much larger and more closely packed. Iguanodon had quite long arms, around 75% the length of their legs, which were strong, and hands that were not very flexible. Their hands were built so that the 3 middle fingers could bear weight when walking quadrupedal. Their hind legs were powerful and they had 3 toes on each foot.

Much unlike the lumbering Polacanthus, a spiky herbivore who regularly accompanied an Iguanodon herd, perhaps for mutual protection, Iguanodon, also herbivores, were one of the most successful dinosaurs ever to have lived. They populated every continent, with the European species probably being the largest and thrived on a variety of vegetation. One of the reasons why they were so successful is that while most herbivorous dinosaurs crudely sliced food with their teeth, Iguanodon were the first herbivores to have developed back teeth which they used to grind up even the toughest vegetation before swallowing. This ability to chew, sped up the digestion of even the toughest plant material.

Iguanodon was an ornithopod, whose intelligence (as measured by its relative brain to body weight, or EQ) was midway among the dinosaurs.

Dozens of Iguanodon fossils were found together, suggesting that they congregated during their lives. Fossils have been found in Europe (in England, Belgium, and Germany), northern Africa, and the USA. Teeth and a few bones of Iguanodon were found in 1822, (perhaps by Gideon Mantell's wife, Mrs Mary Mantell) in Sussex, England. Hundreds of Iguanodon fossils have been found since then.

Many species of Iguanodon have been named, dating from the Kimmeridgian age of the Late Jurassic Period to the Cenomanian age of the Late Cretaceous Period from Asia, Europe, and North America.

Discovered in 1822 and described three years later by English geologist Gideon Mantell, Iguanodon was the second dinosaur formally named, after Megalosaurus. Together with Megalosaurus and Hylaeosaurus, it was one of the 3 genera originally used to define Dinosauria.

Iguanodon was named by Gideon A. Mantell in 1825.