Morphological Modifications Page 4

Lightening of the Skeleton
There is intense selective pressure on flying vertebrates to develop a light body plan. If a pterosaur bone is sectioned and compared with that of a modern bird, one would notice marked similarities. Pterosaur bones are extremely thin walled and are not of uniform thickness. The bones show selective thickening in areas of higher stress. To further reduce weight the bones are also hollow and have a system of internal cross bracing. In the skull there is an additional opening; which have may served to reduce the weight of the large skull.

Cross section through pterosaur bone.

© 1991 Christopher McGowan
Dinosaurs, Spitfires & Sea Dragons.

Some of the larger Pterodactyloids also seem to have pneumatic foramina. This system may have served to help in oxygen exchange in intense physical exertion.



© Patrick Lyons 1998.