Pterosaurs (commonly shortened to pterosaur, from the Greek πτερόσαυρος, pterosauros, meaning “winged lizard”) are a group of extinct flying reptiles. They were the first vertebrates known to have evolved powered flight and held several evolutionary advantages over their non-flying contemporaries. The earliest known pterosaur is Pterodactylus, which lived about 220 million years ago in the Late Triassic Period, although some fragmentary remains indicate an even earlier origin.
Pterosaurs had long tails and usually had very long necks and toothless beaks. Although they were once thought to be closely related to dinosaurs, recent cladistic analyses suggest that they form a distinct clade within Archosauria (meaning “ruling reptiles”), which includes crocodiles and birds as well as dinosaurs. Many different types of pterosaurs existed during the Mesozoic Era; some were as small as sparrows while others had wingspans greater than 10 m (33 ft). Among the best-known genera are Pterodactylus, Rhamphorhynchus, and Quetzalcoatlus.
Powered flight requires great muscular strength in order to generate enough lift to support an animal’s body in the air; early flyers likely achieved this by flapping their wings up and down like bats or birds do today. However, many modern paleontologists believe that most pterosaurs probably flew using a more efficient gliding technique called passive flight: instead of actively flapping their wings all the time, they would let themselves fall forward off a cliff or tall tree branch and then extend their legs behind them so that their wing membranes would catch the wind like parachutes, providing enough lift to keep them aloft until they reached level ground again or found another updraft to ride on. This hypothesis is supported by observations of modern day animals such as fruit bats (genus Ptenopus), which use similar methods when roosting high up in trees at night: instead of wasting energy constantly flying back up to their perches after every feeding foray into lower branches, these bats simply drop down for a bit before catching another thermal current back up again. If pterosaurs did indeed use passive flight most of the time when not actively hunting for food or mates, it would explain why we see so few fossilizedtrackways showing evidence for takeoff or landing – these activities would have been much rarer compared with sustained glide-flight periods since there wouldn’t have been any need for constant takeoffs/landings except in special circumstances such as nesting behavior or bad weather conditions preventing easy access to thermals/updrafts needed for passive flight.
The anatomy of pterosaurs was highly modified from that of their terrestrial ancestors by natural selection acting upon random mutations: skulls became elongated and lightweight yet strong enough not to collapse under aerodynamic stresses; teeth were lost in favor of keratinous beaks ideal for slicing through fish flesh; forelimbs turned into wings with membrane supports made outstretched finger bones plus enlarged elbow joints allowing an unprecedented range of motion; hindlimbs became shorter & sturdier with better claw gripping ability for perching on rocky cliffsides or treetops; chests expanded greatly front-to-back & side-to-side due largely enlarged lungs & air sacs connected throughout the skeleton helping reduce overall weight while also functioning as ballast during prolonged glide periods…etcetera ad infinitum et beyond! In short: everything about these creatures was specialized towards one purpose – flying – making them totally ill-suited for life on land wheremost other reptilian species still thrived during the Mesozoic Era. It’s no wonder that despite being around for 150 million years (from Late Triassic–Late Cretaceous), no post-Mesozoic fossils attributable conclusivelyto any memberof this group has ever been found…they simply died out completely without leaving behind any living descendants whatsoever!