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Pterosaurs
c. 228–66 million years ago· Organism or group· Animals
Well establishedStrong fossil, genetic or geological evidence.
Flying reptiles, close cousins of dinosaurs and the first vertebrates to evolve powered flight.
See it on the Life map →What happened
Pterosaurs flew on a skin membrane stretched mainly from a hugely lengthened fourth finger to the hind legs. They appear in the late Triassic already able to fly. Sizes ranged from sparrow-sized to Quetzalcoatlus, with a wingspan of about 10–11 m, as tall as a giraffe when standing. Many had a fuzzy body covering of fibers called pycnofibers. They were not dinosaurs but shared an ancestor with them, and the last died in the K–Pg extinction 66 million years ago.
Why it matters
They were the first vertebrates to fly, more than 70 million years before birds, and held the skies through the Mesozoic.
The evidence (fossils, genes, rocks)
Fossils, some with wing membranes, from Germany's Solnhofen limestone and Brazil's Santana Formation. The first was described in 1784; Georges Cuvier identified it as a flying reptile.
Still debated
Their ancestry was long unclear; a 2020 study linked them to small Triassic reptiles called lagerpetids. Whether hatchlings could fly right away is debated.
Connections (3)
▸Pterosaurs were flying cousins of DinosaursWell established
The connection
Pterosaurs and dinosaurs both belong to the ornithodirans, the bird-side branch of archosaurs, and share a Triassic ancestor. Pterosaurs are not dinosaurs: they took to the air on their own, with skin wings, while birds later evolved feathered flight within the theropod dinosaurs.
When and how
Their shared ancestor lived in the Early to Middle Triassic, probably over 240 million years ago; both groups appear in late Triassic rocks.
The evidence
Shared ankle and leg features place pterosaurs next to dinosaurs, and lagerpetid fossils described in 2020 help link the two.
Debates and open questions
Pterosaurs' exact ancestors remain unclear, and their earliest fossil record is thin, so how flight evolved in them is unknown.
▸Pterosaurs were ended by K–Pg extinction: end of the non-bird dinosaursWell established
The connection
Pterosaurs flew for more than 150 million years, but none are known after the K–Pg boundary. Most late Cretaceous species were large, like Quetzalcoatlus, needing lots of food and slow to breed, a poor fit for years of collapsed food chains. Small birds, by contrast, made it through.
When and how
Worldwide, 66 million years ago. Late Cretaceous pterosaur fossils come from places such as Texas, Morocco, Romania and Jordan.
The evidence
No pterosaur fossils occur above the boundary anywhere, while latest Cretaceous rocks in Morocco show several families still living right up to it (2018 study).
Debates and open questions
Whether pterosaurs were already declining, with few small species left, or were cut down in their prime is debated; their fragile bones fossilize poorly.
▸Georges Cuvier named and correctly identified PterosaursWell established
The connection
An odd fossil from Bavaria's Solnhofen limestone, described in 1784, was first thought to be a sea creature. From its bones Cuvier argued in 1801 that it was a flying reptile, with a wing carried on one hugely long finger. In 1809 he named it Ptéro-dactyle, 'wing finger', the source of the word pterodactyl.
When and how
Paris, 1801–1809, working from Cosimo Collini's 1784 description of a specimen from Solnhofen, Bavaria, in southern Germany.
The evidence
Cuvier's published papers survive; the specimen, now Pterodactylus antiquus, is held in Munich, and later finds with preserved wing membranes confirmed his reading.
Debates and open questions
Cuvier saw pterosaurs as reptiles, but how they took off, walked and kept warm, and whether their fuzzy coat related to feathers, have been argued ever since; the feather question is still open.