Pterosaur

Pterosaurs were a group of flying reptiles that lived from the Late Triassic to the end of the Cretaceous period, about 228 to 66 million years ago. They are not dinosaurs, but they are close relatives within the Archosauria, the lineage that also includes crocodilians and dinosaurs, including birds.

Pterosaurs varied in size and morphology. The wing consisted of a skin membrane (patagium) stretched between the elongated fourth finger and the body, sometimes supported by the hind limbs. The skeleton was light and hollow, with bones adapted for flight. Some species had pycnofibers, hair-like filaments that may have provided insulation.

Two major clades are recognized: Rhamphorhynchoidea (long-tailed, early forms) and Pterodactyloidea (short-tailed, more diverse, including many later forms). Pterodactyloids dominated later in the record and included several large species, such as Quetzalcoatlus with estimated wingspans up to about 10 meters. Diets ranged from fish and invertebrates to carrion and fruit; dental morphology varied, with early forms often toothed and later pterodactyloids frequently toothless or reduced in teeth.

Flight and ecology: Pterosaurs achieved powered flight and displayed adaptations for both hovering and dynamic soaring in different lineages. Launch methods are debated, with hypotheses including quadrupedal launch or specialized abdominal methods. They occupied a range of habitats, from coastal and marine to inland environments, often near water.

Fossil record and significance: Fossils are found on most continents, with rich records in Late Jurassic and Cretaceous rocks. Pterosaurs represent the earliest vertebrates known to achieve sustained flight and constitute a major archosaurian lineage that disappeared at the end of the Cretaceous.