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Re: Dinosaur urine?



--- Roberto Takata <rmtakata@gmail.com> wrote:

> Dear People,
> 
> I was watching Jurassic Park 3 other day. In a
> scene, the boy lost in
> the Lorna Island show to Dr Grant a flask with T-rex
> pee.
> 
> Well, bird nitrogenous excretion is solid (uric
> acid) and eliminated
> with excrement as the white dielectric material (as
> described by Arno
> and Penzias). How is the N-compounds excretion in
> crocodiles?
> 
> Would a dinosaur produce a watery urine or a pasty
> one?
+++++++++++++++++++++++++++++++++++++

Since no one has addressed the croc part yet.

According to Khalil & Haggag (1958), crocodiles are
ammono-uricotelic (i.e. ammonia is the main liquid
nitrogenous waste metabolite). That they also excrete
uric acid (and it still forms a large portion of the
nitrogenous waste), and lack a urinary bladder and
ureters, I'd say that this was probably a unique
evolutionary adaptation that came about from their
semi-aquatic lifestyle. 

Considering that dinosaurs were neither crocodiles,
nor birds, they probably fell somewhere inbetween,
waste wise. Since both crocs and birds are,
essentially, uricotelic, dinosaurs probably were too.
Though, this does not negate the possibility of liquid
expulsion.

It's possible that some dinosaurs might have had a
urinary bladder of sorts, that they could use to expel
water during times of intense heat (or as an escape
mechanism for smaller dinos). Some turtle species do
this in order to stay cool. It's also possible that
the high humidity level in the Cretaceous reduced
evolutionary constraints on uric acid production, much
like how it seems to have done with extant
crocodylians. 

Overall, though, the incredible amount of
_Postosuchus_ pee seen in WWD, was probably not true.

Jason

"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer

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