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Re: Blood flow in Sauropods



>> 
>> Which raises a question that has always puzzled me.  Why are there no
>> sauropod analogues in Mammalia?  Is this just chance, or was there something
>> about the Mesozoic landscape that favoured the evolution of such huge,
>> long-necked creatures?
>> 
>
>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.

I really can't buy this.  First of all, if this were a true restriction the
giraffe could not exist - but it does, with an extremely long neck still
containing only seven vertebrae.  Secondly, Xenarthrans do possess
intercalary cervical vertebrae, so the "limitation" may not be as limiting
as all that.  Thirdly, even in reptiles you have Tanystropheus which had an
extremely long neck with a rather small number of elongate vertebrae.

Anyway, it isn't just the long neck but the huge size and general form - a
giraffe isn't really a sauropod analogue either, though it's as close as
mammals get, I suppose.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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