Dinosaurs on the Isle of Wight

Over 120 million years ago, the environment that existed on land that eventually formed the Isle of Wight supported a vast biodiversity of life from the smallest bacteria and insect life living in the ferns, cycads and trees to the Sauropods, the largest members of the dinosaur family. The habitat was indeed so perfect for dinosaurs that more evidence of their existence has been discovered on the Island than anywhere else in Europe.

Climate

The climate all those years ago couldn't be more different from todays. The temperature ranged from very warm to hot, in the upland areas it was humid with annual rainfall in excess of 47". In contrast, the lowlands were semi-arid, droughts lasting many months were commonplace and fires would burn uncontrollably until the heavy rains arrived, causing floods and encroachment of swamplands.

15 different species

Despite its diminutive size, the Isle of Wight has yielded the remains of more than 15 different species of dinosaur. The most common are the vegetation loving ornithopods or bird-hipped dinosaurs like the 10m long Iguanodon and the slightly smaller Mantellisaurus which both fed on trees like conifer. The herd loving Hypsilophodon and gazelle-like Valdosaurus (member of the dryosaurid family), living on plant life like cycads and ferns, were also present.

Another plant eater was Polacanthus, an impressively armoured 4m long threophoran dinosaur with rows of spikes along its backbone and the huge, migratory, conifer eating Sauropods.

There is much evidence of Saurischia or lizard-hipped dinosaurs living on the Island. Most of the small Theropods were about 2m long and competed with crocodiles for small animals and hypsilophodontids. The remains of Aristosuchus, Calamosaurus, Calamospondylus and Ornithodesmus have all been found. Of the larger Theropods, the predator Neovenator was over 6m long whilst the spinosaurid Baryonyx was over 9m - evidence suggests both existed in large numbers. Others include Eotyrannus and Thecocoelurus.

Of the bird like Pterosauria dinosaurs, the tail less Istiodactylus had a wingspan of over 4m whilst Caulkicephalus had a crest at the back of its head. Another predator found on the Island is the lagoon and shallow sea loving Leptocleidus at 3m in length. 

Geology

For its size, the Island is of significant geological interest. Tertiary deposits derived from the sea contain detritus such as shells and plants, the bones of fish and turtles, of saurians, or animals of the lizard tribe, and also of some extinct mammalia. Crocodile and shark teeth are also found in this division, as well as wood and the fruit of some former species of the Cycadeae or Pine tribe.

Below the Tertiary Eocene lies the Cretaceous group, which consists of the marine deposits of former oceans, many of them highly fossiliferous. This series is made up of the two beds of Chalk, Upper and Lower, superimposed on Chalk Marl; then follows the Upper Greensand, with its various strata of Chert, Firestone, Limestone, Freestone etc. Below this is the Lower Greensand with formations of Carstone, Sandrock, Ferruginous Sands and Atherfield Clay.

However, it is the Wealdon Group with the Vectis Formation (Wealden Shales) and Wessex Formation (Wealden Marls) that is of particular importance for dinosaur remains. The 11-mile stretch of coastline between Compton and Sandown exposes the Wealdon Outcrop and is the richest source of dinosaur fossils and bones on the Island.

The Vectis formation has three members. The Shepherds Chine member has revealed dinosaur footprints, mostly theropods and ornithopod. In the Barnes High Sandstone member, Iguanodon tracks have been found as well as the rarer theropod. Footprints have also been found in The Cowleaze member.

The Wessex formation has four layers with dinosaur footprints, commonly Iguanodon found in the thin sandstones. Dinosaur vertebrate remains are mostly found in the beds of grey clay plant debris.