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Re: Dinosaur urine?



--- Jura <pristichampsus@yahoo.com> wrote:

> --- 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.

++++++++++++++++++++

Er, forgot to place the full ref in.

For all interested:

Khalil, F.; Haggag, G. 1958. Nitrogenous Excretion in
Crocodiles. J. Exp. Biol. 35 (3): 552-555.

"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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