pterosaurs

Pterosaurs were 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 belong to the larger archosaur lineage that also includes crocodilians and dinosaurs.

Anatomy and flight. Pterosaur wings consisted of a membrane stretched from an elongated fourth finger to the body, sometimes supported by the hind limbs. This wing setup, along with light, hollow bones and a keeled sternum, enabled powered flight. Many pterosaurs had body coverings of hair-like pycnofibers rather than scales. Their flight muscles and skeletal adaptations varied among groups, influencing wing shape and maneuverability.

Diversity and evolution. Early pterosaurs, known as Rhamphorhynchoidea, typically had long tails and smaller bodies, while later groups, the Pterodactyloidea, evolved shortened tails and often larger sizes. The largest pterosaurs belonged to the azhdarchoid clade, with some individuals reaching wingspans of up to about 10 meters. The fossil record shows a wide range of forms adapted to coastal, pelagic, and inland environments.

Ecology. Diets varied among species: small forms fed on insects, many coastal or sea-going species hunted fish, and some large pterosaurs may have foraged on land or scavenged. Reproductive evidence indicates eggs and nesting behaviors, consistent with reptilian life cycles, though direct fossilized nests are relatively rare.

Fossil record and distribution. Pterosaur fossils are found worldwide, with a significant number in Late Jurassic to Early Cretaceous marine deposits. They became extinct at the end of the Cretaceous, leaving no modern descendants.