The Dinosaurs - Iguanodon, an Isle of Wight Iguanodontid

Iguanodon, an Isle of Wight Iguanodontid

Iguanodon

Meaning

Iguana Tooth

Length

10 m (32 feet)

Classification

Ornithopoda,
Iguanodontidae Cope, 1869

Iguanodon bernissartensis Boulenger, in Beneden, 1881

Locations

Iguanodon can be found almost anywhere the Wealden group is exposed. The best bet is to look in the plant debris beds, which are usually light grey, with bits of black lignite in them.

Iguanodon was a herbivorous dinosaur, feeding on the plants, such as conifers, cycads and tree-ferns that are found in the Wessex Formation. Iguanodon were capable of walking on four legs or two, with I. bernissartensis preferring quadrupedalism.

There are large spikes on the thumbs, which may have been used for defense, but there is possible evidence for intraspecies fighting, with the spikes being used on competitors for mates.

As one of the most common dinosaurs in the Wealden, let alone the Isle of Wight, there is quite a lot of this.

The distinguishing features of Iguanodon are in the skull, pelvis and foot, so most material is assumed to be Iguanodon just because it’s so common. The teeth can reach up to 40 mm (1½ inches) in height, and show an expanded crown and fine denticulation. The teeth of different jaws have different wear marks. On the upper jaw there is a prominent keel in the labial (outer) surface, where as in the lower jaw the teeth have two less prominent ridges on the lingual (inner) surface.

The skull is deep and robust with a laterally compressed snout, with the premaxillae and predentary forming a spoon-shaped beak with serrated margins. The quadrate is pillar-like. There were prominent palpebrals, and secondary palpebrals behind them, which is possibly unique to I. bernissartensis. The hands are large and robust, with an elongate conical thumb-spike. The phalanges of the second, third and forth fingers are shortened, with hooves on digits two and three.The forearms are 50-75% the length of its hindlimbs. The foot is tridactyl , with no hallux or fifth digit, and examples of their footprints can be seen at Hanover point. The vertebrae have short neural arches.

Iguanodon skin has also been found, which has a rough pebble-like texture.

Until 2006, there were believed to be two species of Iguanodon found on the Isle of Wight, I. bernissartensis and I. atherfieldensis. I. atherfieldensis has since been removed from the genus Iguanodon and so has been renamed Mantellisaurus atherfieldensis, which can be found HERE

NAISH, D. and MARTILL, D. M. 2001. Ornithopod dinosaurs. In MARTILL, D. M. and NAISH, D (eds). Dinosaurs of the Isle of Wight. The Palaeontological Association. Field Guide to Fossils 10. 60-132

NORMAN, D. B. 1980. On the ornithischian dinosaur Iguanodon bernissartensis from the Lower Cretaceous of Bernissart (Belgium). Mémoires de l’Institut Royal des Sciences Naturelles de Belgique, 178, 105pp.

PAUL, G. S. 2006. Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England; In CARPENTER, K. (ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Indiana University Press, Bloomington. 69-77