Life in the Air 2

The pterosaurs seem to have had the same kind of brain development as birds, and like the birds had a well-developed sense of sight with a poorer sense of smell.

Pterodactylus, a pterosaur.

Hairy bodies and wings

Many palaeontologists believe that the pterosaurs were also warm-blooded like birds. If they were, then they would probably have needed an insulating cover of feathers or fur. Long ago, pterosaur fossils were found which some people believed showed slight traces of hair, but in 1970 a small fossil was found in Jurassic rocks from Russia which settled the matter. The fossil, named sordes pilosus, was preserved in remarkable detail and showed not only clear impressions of the wing membranes but also of a thick coat of fur over the body and wings.

We have no direct evidence on the breeding habits of the pterosaurs, but since both birds and bats need to be looked after by their parents until they are fully developed and can lead an independent flying life, this was probably also true of pterosaurs.

Reducing weight

The earliest good fossils of pterosaurs come from rocks of the early part of the Jurassic period. These animals had fairly heavy skulls with many teeth, and long bony tails, sometimes with a small rudder at the tip. In the late Jurassic and the Cretaceous, many pterosaurs seem to have lost both teeth and tail, probably in order to reduce their weight and fly efficiently as they became larger.

Small species

The Jurassic species were mostly small, some no larger than sparrows. They flew by flapping their wings, probably more slowly and less powerfully than birds do. In cretaceous times most of the pterosaurs had become specialized for a gliding and soaring flight. This led to the development of long, narrow wings and to a great increase in size, so that the Cretaceous pterosaurs were the largest animals to have ever flown in the air.

Pteranodon

One of these pterosaurs from the later part of the Cretaceous was pteranodon from Kansas in the United States. It weighed about 18 kilogrammes and had a body about the size of a turkey's, with a wing-span of 7 metres. Its long beak was balanced by a crest rising from the back of its skull. Pteranodon seems to have led the same sort of life as an albatross, flying far out to sea, being perfectly adapted for gliding and soaring, but having hind legs too spindly for walking any distance. Pteranodon probably lived on offshore islands where it could rest and rear its young in safety, but spent most of its time at sea, catching fishes at the surface.

Until quite recently it was believed that no animal bigger than pteranodon could ever have flown. But since 1972, excavations in Texas have revealed remains of a pterosaur with an arm bone twice the length of pteranodon's. It has been named quetzalcoatlus, and estimates of its wing-span range from 10 to 15 metres. It lived far from the sea and is believed to have behaved like giant reptilian vulture, soaring high in the air and watching for dying animals such as dinosaurs, so that it could scavenge off their decaying carcasses.

Pteranodon