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Pterosaurs waddled when they walked?

Pterosaurs waddled when they walked?

When the dinosaurs ruled the earth, pterosaurs (wingedreptiles) were masters of the sky. Once envisioned as simple reptilian gliders, pterosaurs have recently been identified as warm-blooded, energetic and proficient fliers.

But while pterosaurs may have been agile in the air, David M.Unwin of Reading University in Britain concludes in the May 7 NATURE that, on the ground, they "could manage only a clumsy waddle' and had neither the stance nor mobile gait of fully erect birds. Consequently, he writes in NATURE'S News and Views section, they spent most of their lives hanging from trees and cliffs.

Unwin bases this conclusion in part on two relativelyuncrushed pterosaur pelvises that were discovered recently in West Germany and Australia. In these pelvises, the acetabulum, or socket into which the tip of the femur bone fits, is oriented outward and upward, suggesting that pterosaurs' legs were splayed out, giving them a clumsy, sprawling gait, writes Unwin. Had the acetabulum pointed out and down instead, the pelvises would have supported an alternative theory, held by some since the 1970s, that pterosaurs stood erect with their hind limbs beneath their bodies and were capable of agile movement on the ground.

Unwin argues that pterosaurs were probably good climbersand, like bats, probably began their evolution to flight from the trees. However, he cautions that analogies to bats, and to birds as well, should not be extended too far, since pterosaur anatomy is quite different. Pterosaurs, he writes, "appear to have solved the problems of aerial, vertebrate existence in a very different, uniquely pterosaurian way.'
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Title Annotation:dinosaur research
Publication:Science News
Date:May 30, 1987
Words:263
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