Bernissart's igauana tooth
Cretaceous Period, 126-125 MYA
North America, Portugal
Countries in North America, and Portugal
33 feet long, 10 feet tall at the hips, 3 tons
- Over the years, there has been much debate of the posture of Iguanodon. When first discovered and believed to be a lizard, it was depicted with stumpy legs and a dragging tail. Upon realizing that the forelimbs were noticeably shorter than the hind limbs, the view changed that animal was a biped that used its tail to help keep itself upright much like a kangaroo. However, to achieve a tripodal position would require the animal to break its own tail.
- The hands are poorly built for grasping or manipulating food and end in hooflike nails.
- Coupled with a robust pectoral girdle built to bear weight, it is now known that Iguanodon spent most of its time in a quadrupedal posture with legs directly underneath the body and tail raised off the ground, although it could locomote on two legs if it needed to.
Iguanodon was the second dinosaur ever discovered. Gideon Mantell came up with the name due to the fact the animal’s teeth resembled those of the modern iguana. The most distinguishing feature of Iguanodon is the large spike located on the thumb. Early depictions placed this structure on the animal’s nose. The exact function of the spike is unknown but it is believed to have been a weapon used to defend the animal from predators or possibly to compete with rival Iguanodon. Animals like Iguanodon represent a transitional form of ornithopod in between the small, swift-running hypsilophodontids that appeared in the mid Jurassic and the crested hadrosaurs of the Cretaceous.
Kingdom - Animalia Phylum - Chordata Class - Reptilia Order - Ornithischia Family - Iguanodontidae Genus - Iguanodon Species - I. bernissartensis