The fossil, which is a segment of tooth, has been at the museum since 1884 but has never been thoroughly examined before.
It now has scientists thinking the extinct flying reptile had a wingspan of up to seven metres, two or three metres bigger than previously thought.
David Martill from the University of Portsmouth and David Unwin from the University of Leicester reported the discovery in the journal Cretaceous Research.
'Early pterosaurs were relatively small, with wing-spans not much bigger than a crow,' said Dr Martill. 'These early pterosaurs all had a mouth full of teeth, usually small at the back and larger at the front.'
The fossil fragment was uncovered during the 19th Century in Cambridge, and was given to the Natural History Museum by renowned fossil hunter Sir Richard Owen who helped found the museum and coined the word 'dinosaur'. Read More