Iguanodon

## Physiology

### Attributes

Thumb spike-lie claw; chewing teeth; walks on four legs, however, runs on two legs

## Biography

### Time

145 to 70 MYA

***Iguanodon*** (name meaning "*Iguana Tooth*") is a genus of ornithopod dinosaur that originated during the Early Cretaceous period in what is now the world continents. A herbivorous dinosaur that measured around 10 meters long, weighed 4 tons, and resembles a combination between the swift bipedal hypsilophodontids and the duck-billed hadrosaurs, *Iguanodon* is very well-known as one of the first dinosaurs to be identified by science, recognizable by its large thumb spike. It is also said to have been arguably the most successful dinosaur that ever lived; a dinosaur that walked on four legs and ran on two and is a distant relative of the Hadrosaur family of dinosaurs.

In the episode "*The Great Migration*", several individuals of each species of *Iguanodon* were lived in their lifes from Early Cretaceous South America, North America, and Europe, 127 million years ago.

## Facts

### Era & Discovery

*Iguanodon* lived in essentially all the world continents during the Early to Late Cretaceous period from 145 – 65 million years ago. *Iguanodon* was a very successful dinosaur. In fact, they were among the most successful dinosaurs that ever walked the Earth, having existed for 80 million years throughout the Cretaceous, inhabiting all the world's continents and prospering in various plants and vegetation. However, they were prey animals for carnivores such as *Sarcosuchus*, *Deinonychus*, *Utahraptor*, and the immense *Giganotosaurus*.

*Iguanodon* was named in 1825 by English geologist Gideon Mantell but discovered by William Harding Bensted. Since its discovery, *Iguanodon* has become one of the most well-known dinosaurs in the world.

### Physical Attributes

While there were several species of *Iguanodon* all across the globe during the Cretaceous period that varied in size and appearances, *Iguanodon* was nevertheless a large and bulky herbivorous dinosaur with chewing teeth, thumb spikes, and could shift from biped to quadruped.

All species of *Iguanodon* weighed around 3 – 4 tons (6,000–8,000 lbs.), but the North American species, named *Dakotadon lakotaensis* (name meaning "*Dakota Tooth*"), was the smallest, measuring about 30 feet (9 m) long and standing 10 feet (3 m) tall at the hips. The larger European species, called *Iguanodon bernissartensis* (name meaning "*Iguana Tooth*"), was 33 feet (10 m) long and 11 feet (3.4 m) tall at the hips. The largest was a South American species known as *Macrogryphosaurus gondwanicus* (name meaning "*Big Enigmatic Lizard*"), measuring 36 feet (11 m) long and standing 12 feet (3.7 m) tall at the hips.

Contrary to what was previously thought, although these herbivorous dinosaurs walked in a quadrupedal stance, they were capable of running in a bipedal manner. And this makes them quite nimble, more so than slow-moving dinosaurs like the ankylosaurs, such as *Polacanthus*. *Iguanodon* had long hind legs, shorter front legs, and a long head with a blunt beak. Inside its mouth was a large battery of teeth designed to grind plant matter rather than to just rake the leaves off. On their front legs, the thumbs were spikes and acted as a last line of defense against predatory dinosaurs.

### Behavior & Traits

Like many herbivores, *Iguanodon* were social animals that lived in vast herds, with as many as hundreds of thousands of individuals in a single herd, as a method of protection due to the fact that individually, they had barely any weapons or means of defense. The young often played around adults. As a herd, however, these dinosaurs could stampede, overrunning their predators and trampling them into the ground. However, living in these large herds, they would also have constantly migrated to find new growth to feed on.

*Iguanodon* was preyed upon by the large predator *Giganotosaurus*, the massive crocodile *Sarcosuchus*, and the dromaeosaurs *Deinonychus* and the giant *Utahraptor*. However, whilst it had to use speed against *Giganotosaurus* and *Sarcosuchus*, *Iguanodon's* bulk and weight may have helped it shake off a single attacking *raptor*. On the other hand, if there were multiple *raptor*s attacking it at the same time, it would stand little chance.

One particular reason *Iguanodon* were as successful as they were is that they developed a new way of dealing with plants in the Cretaceous. Whereas most dinosaurs, carnivore or herbivore, could only crudely slice food with their teeth, *Iguanodon*, however, was the first herbivores, let alone dinosaur, to have developed back teeth designed to grind up the vegetation before swallowing. This ability to chew sped up the digestion of even the toughest planet material.

## Gallery

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## Trivia

* The sound effects of *Iguanodon* are that of the sounds featured in the Disney movie "*Dinosaur*".