"Pterosaurs were flying reptiles of the clade [group] or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period (220 to 65.5 million years ago).
Pterosaurs are the earliest vertebrates known to have evolved [developed] powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the legs to a dramatically lengthened fourth [actually fifth] finger. Early species Rhamphorhynchoidea had long, fully-toothed jaws and long tails, while later forms Pterodactyloidea had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like [feather-like] filaments known as pycnofibres, which covered their bodies and parts of their wings. Pterosaurs spanned a wide range of adult sizes, from the very small Nemicolopterus to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx.
Pterosaurs are sometimes referred to in the popular media as dinosaurs, but this is incorrect. The term "dinosaur" is properly restricted to a certain group of terrestrial reptiles with a unique upright stance (superorder Dinosauria), and therefore excludes the pterosaurs, as well as the various groups of extinct aquatic reptiles, such as ichthyosaurs, plesiosaurs, and mosasaurs.
Traditionally, they are organized into two suborders:
- Rhamphorhynchoidea: A group of early, basal ("primitive") pterosaurs, many of which had long tails and short metacarpal bones in the wing. They were small, and their fingers were still adapted to climbing. They appeared in the Late Triassic period, and lasted until the late Jurassic.
- Pterodactyloidea: The more derived ("advanced") pterosaurs, with short tails and long wing metacarpals. They appeared in the middle Jurassic period, and lasted until the Cretaceous-Tertiary extinction event [when they developed into modern birds].
"Ramphorhynchoids were the first pterosaurs to have appeared, in the late Triassic Period. Unlike their descendants the pterodactyloids, most rhamphorhynchoids had teeth and long tails, and most species lacked a bony crest, though several are known to have crests formed from soft tissue like keratin. They were generally small, and disappeared at the end of the Jurassic Period."
"They appeared during the middle Jurassic Period, and differ from the basal rhamphorhynchoidea by their short tails and long wing metacarpals (hand bones). The most advanced forms also lack teeth. Many species had well developed crests on the skull,"
"Other distinguishing characteristics that set Pteranodon apart from other pterosaurs include narrow neural spines on the vertebrae, plate-like bony ligaments strengthening the vertebrae above the hip, and a short tail in which the last few vertebrae are fused into a rod."
" A new compilation of data for the Lower Cretaceous hints at a broad differentiation between pterosaurs that lived in continental habitats (anurognathids, ctenochasmatoids, dsungaripteroids) and those that frequented marine environments (ornithocheiroids). Moreover, there is evidence of further differentiation within continental habitats, between pterosaurs living in lowland and coastal regions (anurognathids. ctenochasmatoids) and those living in more inland environments (dsungaripteroids). "