PETRIFIED RELICS TELL THE HISTORY OF THE EARTH

Pterosaurs
Pterodactylus kochi

The pterosaurs were the first vertebrates to learn to fly. They evolved during the Triassic (some 200 Million years ago), probably from tree-dwelling reptiles which were capable of gliding. The first pterosaurs, found in Lower Jurassic beds in England some 180 Million years in age, had already all the typical characteristics of the group: the bone structure was very light, the large skull was only a framework of bony rods, and the hands were modified into flying organs by the extreme elongation of the fourth finger.

A flying membrane stretched bitween this finger and the side of the body. The first three fingers were short, freely movable and furnished with sharp claws for holding on to trees and rock surfaces.
A primitive character was the long tail, at the end of which was a rhomboidal rudder.

In Pterodactylus, which could be as small as a sparrow or as large as a vulture an which first appeared in the Upper Jurassic (some 150 Million years ago), the long bony tail had almost disappeared. Pterosaurs are found in the lithographic limestone quarries of Solnhofen and Eichstätt but are very rare there; they include not only the short-tailed forms but also longtailed species (Rhamphorhynchus spp.). During the Cretaceous (from 140 to 70 Million years ago) the pterosaurs attained gigantic proportions; Pteranodon, of almost 8 Metres wing-span, was the largest flying animal of all time. Before the end of the Cretaceous the pterosaurs became completely extinct and their place was taken by the rapidly evolving birds.

Original: Museum of Natural History, Vienna, Austria

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