Pterosaurs are commonly referred to as Pterdactyls. However scientists prefer Pterosaurs so this name is used in this book.
Pterosaurs are not dinosaurs, but a close relative. They lived alongside dinosaurs and died out at the same time.
On the Ground 
As well as flying, Pterosaurs could move on the ground. But for a while scientists didn't know if this was using two feet (bipedal), or using four feet (quadrupedal). We now know that they used four, from fossil footprints. However, we don't know if they did this all the time. Some scientists think that small Pterosaurs could walk or even run on two feet, but larger ones used all four like bats do now.
Body shape 
The different types of pterosaurs all had different sizes. Ranging from 0.75m wingspan and of the Pterodactylus to 11 metres wingspan and 135 kg weight of the Quetzalcoatlus. Quetzalcoatlus was the largest pterosaur, its wingspan being 45 feet.
The pterosaurs are divided into two groups; the Rhamphorhynchoids had no crests and tails, while the Pterodactyloids had crests but no tails.
Most large Pterodactyloids had crests on their head, possibly colored brightly, but different types of Pterodactyloids had differently shaped crests. All were narrow, but some stretched out behind their head in a triangle shape (as in the picture on the left), while others were small rounded humps on top of their heads.
They didn't have feathers, but almost all scientists even think they might have had fur, like bats! They might have been for warmth, just like bats!
What did they eat? 
Pterodactyls were carnivores and scavengers. In the first few months of their life, they ate insects. As an adult they ate a lot of fish which they would catch from the surface of the water by dipping their long beaks in as they flew over, but they would also eat dinosaurs who were already dead.
When did they live? 
The Pterosaurs lived all through the mesozoic era. The Rhamphorhynchoids lived in the Triassic and early Jurassic periods; and the Pterodactyloids in late Jurassic and Cretaceous periods.
Where did they live? 
They most probably lived close to the sea shores so that they had easy access to fish. They also may have lived in large groups like some modern sea birds. Though some scientists have found fossils of Pterosaurs in caves.
When and how they were discovered? 
Different types of pterosaurs were discovered at different times. The earliest to be found was the Pterodactylus in 1784 in France by the Italian scientist Cosimo Collini. He didn't think they could fly but thought they could swim. This seems silly now that we know they have wings. Another species was discovered in 1876 by Othneil C. Marsh, and one of the most recently discovered the gigantic Quetzalocatlus found by Douglas A. Lawson. New discoveries are still being made; in the 1990s there were several discoveries made to suggest that even a larger pterosaur could have existed than previously known (Arambourgiania philadelphiae).
How were they wiped out? 
The last of the larger Pterodactylids seems to have been killed in the K-T extinction, along with the dinosaurs. However, the Rhamphorynchids seem to have been extinguished earlier, probably because they could not compete with birds (which evolved around that time).
What do we need to learn? 
- What colour were they?
- What were the crests on their heads used for?
- Were they really scavengers?
- Were they covered in fur?
- Could they fly great distances or only short distances?