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Re: Blood flow in Sauropods




> At 12:05 AM 9/14/95, Derek Tearne wrote:
> >The reason which I have heard cited is that mammals are restricted to
> >7 vertebra in the neck and no mammal has more (although I knew a
> >woman once who had eight... ).
> >
> >This pretty much restricts the length and flexibility of mammalian necks.
> >
> >Birds, reptiles and dinoraus are not restricted in this way and
> >can therefore evolve much longer necks.
> 
>         I can't say i've heard this before -- just precisely what does
> "restricted" mean?  Is this supposed to mean that it's physically
> impossible for mammals to evolve more (or less) than seven cervicals?  How
> would one determine such a limit?  After all, most of the long-necked
> sauropods have similar numbers of cervical vertebrae, except for
> _Mamenchisaurus_ (I'm not sure about other euhelopodids) which went and
> increased it from 12ish to 19.  Under the proper selective potentials, I'd
> think that a mammal could and would do something similar.
> 

      Also, a giraffe doesn't exactly have a short neck.  I imagine a 
mammal could make a neck as long as it wanted, if it was willing to 
sacrifice flexibility.

J.Martz