The dominant aerial creatures on Earth for over 160 million years. They were also the largest flying animals that have ever lived. Some are estimated to have reached a wingspan of 13 metres, though it is more than likely that these highly debated and cautious estimates would have been exceeded, and many Palaeontologists are beginning to agree with those amongst them who where once criticised for their outlandish theories, who believe wingspans of over 15 metres – possibly up to 17 metres – were likely. These monstrous flying reptiles were doubtlessly graceful creatures, of a time before Birds evolved, though they did share the skies with the Birds towards the End of the Cretaceous. Despite some being huge, others were tiny; Anurognathus was a Jurassic Pterosaur, a small as a common bat, and similar in appearance.