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The Isle of Wight pterosaur
 The Isle of Wight pterosaur
The new Isle of Wight pterosaur
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Mesozoic flying reptiles
The team's first of two visits to the Isle of Wight for the Big Monster Dig series was on the trail of a pterosaur. Pterosaurs were the mighty flying reptiles that soared the Mesozoic (see Timeline) skies. This programme was special to Dave Martill as pterosaurs are one of his pet subjects and the Isle of Wight is his home territory.
As with many really important fossil finds, the crucial discovery had been made by an amateur fossil hunter. In this case, it was by a young lad called Dan Davies, who had been on the beach during a family holiday and whose keen eyes had spotted what turned out to be a pterosaur's wing bone.
Some of the local fossil hunters had a good idea of where the rest of it might be. So Sarah Gabbott was dispatched to dig with them while Dave took Dan's piece to the nearby Dinosaur Isle visitor centre to compare it with some other bones that had been found on the island. John Howell, in the meantime, decided to get a pterosaur's-eye view of the geology in order to help understand what was going on.
Colour-coded geology
The marvellous thing about the Isle of Wight for geologists is that its geology is colour-coded. The backbone of the island is a hard ridge of white chalk. This separates the younger orange, red and green Tertiary-aged rocks (see Timeline) that make up the north of the island from the older red and grey dinosaur-bearing rocks that make up the south.
From the plane John could easily see that the northward-dipping layers rose up in sequence: the red layers of the Wessex Formation, followed by the dark grey deposits of the Vectis Formation, and finally the pure white of the Chalk Formation. This upward change in colour represents a gradual but steady rise in sea level over a 30-million-year period.
The lower beds containing the pterosaur finds were laid down in a flood plain with meandering rivers winding their way across fertile flat lands. The grey deposits of the Vectis represent the point at which the rising sea started to flood the land and it became more of a coastal lagoon. Further sea-level rise flooded the whole island and most of north west Europe.
The chalk deposits represent the remains of billions (actually millions of billions) of tiny, floating microscopic plants called coccolithophores that lived in that sea. Sea levels in the late part of the Cretaceous (see Timeline) were at an all-time high. The climate was very warm and virtually all the glaciers at the poles had melted. Much of what we know as land was under water; Earth was a greenhouse planet.
Eagle-eyed locals
Back at the site, Sarah wasn't having too much success – which may have been because the eagle-eyed locals had already been on the case. Dave tried to discover what else had already been found and removed. Local collector John Winch, for example, had found a piece of pterosaur jaw, which Dave matched exactly to a piece that had been donated to the museum by another local man, Gavin Leng. In fact, when Dave and Laura started to put all the pieces together it seemed that Dan's fossil wing bone was also probably part of the same specimen. Now all they had to do was work out what type of bird it was and what was the purpose of the strange crest on its head.
Sarah turned her attention to the crest, enlisting the help of some local school children. They made a variety of balsa wood models with different crest shapes and tried to fly them. Much to the children's surprise, the models with a big crest didn't fly well; in fact, the crest would have been a positive disadvantage to the bird. It must have served a different purpose and one more important than flying.
The only thing more important than flying to a pterosaur would have been finding a mate. And indeed, when the children, painted the crests with bright colours it was clear that the one with the biggest crest looked most impressive. The crest had clearly been used for display purposes.
The team still didn't know what species of pterosaur it was, and Dave was rapidly crossing off known pterosaurs from his list. He compared it to the other samples at the Dino Isle Museum and quickly ruled out any of the species that had been found on the island previously. He then took it across to Portsmouth University and compared it to his collection there. He still couldn't find a match. Finally, he paid a visit to the Natural History Museum in London to see if it matched up with any known species there.
'Sieving Steve Sweetman'
At the same time, John headed off to see 'Sieving Steve Sweetman'. Steve, who also lives on the island, gets his name from his passion for taking buckets of sediment and washing and sieving them. He then painstakingly picks though all the pieces looking for tiny fossils – with amazing results. While Dave seeks out the big fossils, Steve looks at all the tiny bones from the frogs and small mammals that also occupied the dinosaurs' Cretaceous world.
An entirely new pterosaur
It was Dave, however, who had the pleasure of announcing, after his Natural History Museum visit, that this particular pterosaur was something special. Not only had nothing quite like it been identified previously on the Isle of Wight; it was actually an entirely new species and potentially an entirely new genus – the first of its kind found anywhere in the world.
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