Iguanodon were large herbivorous dinosaurs, the transition from movement on two legs for movement on four. The most famous member of the genus, I. bernissartensis, could weigh about 3 tons and reach a length of 10 meters on average. The largest specimen had a length of 13 meters. Other species were smaller: I. dawsoni in length only grow up to 8 meters, I. fittoni - 6.
In front of the jaw iguanodons had a beak, composed of keratin, followed him teeth, teeth like an iguana, but larger and more frequent.
The forelimbs were about a quarter shorter than the rear, the three central fingers on them have been adapted for support. Located on the thumb spikes, presumably used for protection. At the beginning of the XIX century, these were considered the horns, and spikes were placed on the nose animal paleontologists, the truth of their situation was shown later. "Little Fingers" as opposed to the rest of the fingers were long and flexible.
On hind legs adapted for walking, but not for running, there were only three fingers. Spine and tail were supported by ossified tendons.