Pterodactyl
'Winged finger'
Description
A Pterodactyl had a wingspan of anywhere between a few inches up to over 40 feet long. Pterodactyls are believed to have flown long distances using large wings and they had above average eyesight to help them catch their prey. Paleontologist classify Pterodactyls as flying reptiles and not dinosaurs.
It's unclear at what point "pterodactyl" became a synonym for pterosaurs in general, and for Pterodactyl-us and pteranodon in particular, but the fact remains that this is the word most people (and Hollywood screenwriters) use. Working paleontologists never refer to "pterodactyls," instead focusing on individual pterosaur genera (and woe betide any scientist who confuses Pteranodon with Pterodactylus!)
Reason for extinction.
Pterodactyls, along with the dinosaurs, marine reptiles, and other groups of life, went extinct roughly 65 million years ago, at the end of the Cretaceous. The prevailing line of thought for the cause is that a 6 mile wide meteor hit the Earth--the resulting crater is believed to be Chicxulub, in the Yucatan Pennisula. The impact would have sent up a thick plume of debris, blocking out the sun for months, maybe even years. No sunlight, no plants; no plants, no plant-eaters, and so on. TheImpact Theory is still debated, with some paleontologists believing that environmental change brought about the K-T extinction 65 million years ago, while others believe that dinosaurs and their kin where on the decline before the K-T boundary, but seeing as the only place where paleontologists can access a fossil-bearing formation that has numerous fossils from the end of the Cretaceous is in the Hell Creek Formation, there isn't much data to support the declining theory.
Lifestyle
The pterodactyls tended to live in caves and trees. They ate large insects and lived near the sea. The leathery material over their long arms caused them to be able to fly quickly. They were one of the only flying reptiles during the period of the dinosaurs. The wings of a pterodactyl are not like that of a bird. Pterodactyls had 4 "fingers" and three of them would end at about half of the wing. The last finger would extend out to the very end of the wing.