EEB267H1 Lecture Notes - Lecture 21: Femur, Weak Interaction, Metatarsal Bones
28 Mar 2017
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Document Summary
No bladder: cannot store urine (water) Birds produce uric acid to get rid of nitrogen (waste) in the kidneys. Urine is pasty and white: full of uric acid, do not require water. Relatively small and many (usually 9) air sacs. Pneumatic bones: air-filled bones, air cavities in cranial bones are not unusual in amniotes, what is unusual is the projections of air-filled sacs in the postcranial bones. Widespread in dinosaurs: birds have taken it one step further - projections in vertebrate as well as other bones. Pneumatic bones are very thin-walled and hollow: contain a series of internal braces for strength. However, bird bone is very dense: bone tissue is much denser, but hollow - balances out the hollowness, bird bones weigh the same, but is much stronger for flight. Some bones lost, others reduced in size. Less bone in skull: short, but large to hold the big brain, big eyes, no teeth.
