"Thick" isn't the right word, probably. Modern birds have bones that are hollow, to aid flight. Dinosaurs have non-hollow bones (thick bones). The Archaeopteryx has non-hollow bones.
This isn't entirely correct. First of all, one has to make a distinction between hollow bones, and
pneumatic bones, in which air sacs involved in the pulmonary system invade the interior of the bone. Living birds have extensive pneumatization, and there's no consensus as to whether it's related to flight or not. Archaeopteryx had hollow long bones and limited pneumatization, and in non-avian theropods, which also had hollow long bones, pneumatization was limited to certain vertebrae and ribs.
Christiansen, P., & N. Bonde. 2000. Axial and appendicular pneumaticity in
Archaeopteryx. Proceedings of the Royal Society of London, Series B 267:2501-2505.
O’Connor, P. M., & L. P. A. M. Claessens. 2005. Basic avian pulmonary design and flow-through ventilation in non-avian theropod dinosaurs. Nature 436:253-256. Available
here.
Edited by Augray, : Edit stupid spelling mistakes.
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