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Re: Dinosaur urine?

Dan Pigdon wrote:

That depends on whether the system found in birds is an adaptation to flight
or not. Excreting a paste in flight would seem to be easier than urinating or
passing solids, and being able to squirt it out at speed no doubt helps
prevent feathers being fowled.

What is the evidence that this is a flight adaptation? Birds process waste very differently than flying mammals. For example, birds excrete nitrogenous waste from the blood as uric acid rather than urea dissolved in urine and eliminate all wastes through a single vent. These are big differences. I'm speculating, but the *paste like" results from the bird system would seem to be more fundamental to the basic avian physiology than to adaptations for flight, per se. Interesting question though. Any evidence of combined uric acid and fecal secretions from coprolites attributed to derived theropods?