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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
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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

http://members.tripod.com/~jurassosauridae/index.html

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