The average pterodactyl had a wingspan of 3 feet and weighed between 2 to 10 pounds. Pterodactyls were not dinosaurs, though both groups belong to the same scientific grouping, the archosaurs.
Pterodactyls were flying reptiles with bat-like membranes that stretched across their front limbs. Although some people may use the terms "pterodactyl" and "pterosaur" interchangeably, pterosaurs were the overarching group to which pterodactyls were merely members. Some pterosaurs grew to great sizes, with heights comparable to giraffes.
Pterodactyls appear to be among the smaller members of the pterosaur group. However, as of 2015, scientists have not unearthed any fossilized adult pterodactyl specimens, so it is possible that fully grown individuals exceeded the currently known wingspan and weight. There are currently two widely recognized species of pterodactyl: Pterodactylus antiquus and Pterodactylus longicollum. Of these, Pterodactylus longicollum is the largest.