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Re: [RE: Reptile-Bird-Dinosaur-Penis Connection]

Jack <jconrad@lib.drury.edu> wrote:
> -----Original Message-----
> From: Ben L.
> (mass snippage below)
>   Most male reptiles have some sort of penis-like
> structure(s) for internal fertilization.  Male birds
> lack such an organ and only use a cloaca kiss.  
> [...]
>  I'm only in a high school biology AP class, so my
> reasoning and information may not be all correct.  So
> I'm posting these hypothesis on the List -- would the
> experts take a look and see if my thinking makes any
> sense?  Thank you.
> =================
> Your reasoning isn't too bad, some of your info (I believe) isn't quite
> right because some male birds do retain a penis.  These birds include
> ostriches and ducks, among others.  This seems to indicate a relationship
> between flight and the presence or absence of this structure.  It is also
> interesting to note that large terrestrial reptiles (including birds like
> the ostrich) generally have larger males members than females.  You can see
> it in crocs and ostrich.  Why would volant birds have larger females?
> The answer may lie in flight.  Birds that can mate on the wing with a
> "cloacal-kiss" can afford to have smaller males than females, may actually
> require it.  The female needs to be bigger because of the eggs she
> carries--she must be strong enough to carry the added load.  Males, lacking
> such a need, are able to be smaller.  Ostriches, which must mate on the
> ground, have larger males than females.  This makes sense too, if you cannot
> easily coordinate a cloacal-kiss (rather difficult on the ground) and are
> going to have to implement a penis, you want the male to be larger. 
> Actually, this has been my argument against always suggesting that the
> larger morph of theropods was the female.  It doesn't hold for terrestrial
> birds and if you look at crocs, you see the same thing.  
> jack

True, but we also see reverse size dimorphism in chelonians as well. Females
turtles tend to be larger than males, and turtles have penises (or is that
peni?) too.

Archosaur J

Jurassosaurus's Reptipage: A page devoted to the study of the reptilia


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