• Sierra del Carmen

    Big Bend

    National Park Texas

Pterosaur Lifeways


Pterosaur Lifeways
The earliest known pterosaurs lived about 220 million years ago in the Triassic period, and the last ones died about 65 million years ago at the end of the Cretaceous period. They ranged from pigeon-sized with a wingspan of 18 inches to ultralight-airplane-sized Quetzalcoatlus with a wingspan of 36-39 feet. Exceptionally well-preserved fossils have shown that pterosaurs were covered with hair.

Pterosaurs were the first vertebrates to adapt to a life of active flight. Only two other groups of vertebrates are active fliers, namely birds and bats. Despite the unavoidable comparison of pterosaurs with birds, it is important to note that they are very different animals that followed different evolutionary pathways. In fact, the early birds existed at the same time as some of the pterosaurs, but birds managed to survive the mass extinctions at the end of the Cretaceous period while pterosaurs did not.

Flight tests with models of Quetzalcoatlus suggest that it was primarily a soaring creature controlling its direction by turning its head, flexing the three fingers on the wing's leading edge, and warping the wing tip. These giants, the last of the flying reptiles, were able to climb or dive by changing the wing sweep, but were probably unstable in gusty winds.

Some pterosaurs probably were carrion-eaters, at least on an opportunistic basis. Although it may be tempting to compare the giant Quetzalcoatlus with large modern birds such as condors and eagles and conclude that, like them, it too ate carrion, the anatomical evidence does not support this. Quetzalcoatlus had a long inflexible neck that would not have been desirable for vulture-like feeding. Its long, tweezer-pointed, and toothless jaws were not suited for tearing apart dinosaur cadavers, and are more suggestive of a diet of fish. But this observation creates another puzzle because the Big Bend fossil sites were some 250 miles from the sea coast at that time. Dr. Wann Langston proposes that Quetzalcoatlus used its slender beak to probe for molluscs and arthropods in shallow flood basins. His view is supported by numerous traces of burrowing animals in the strata in which the Quetzalcoatlus fossils were found.

Did You Know?

The landslide is clearly visible for miles

The landscape of Big Bend National Park appears to lie stable and quiet, yet the relentless force of erosion continues to wear down the mountains. In 1987 the late evening silence was shattered by a rumbling rockslide, heard for miles. A large scar on the Santiago Mountains marks the spot. More...