RE: Pelicosaurs: sprawling or not?

["Steve Brusatte" <dinoland@lycos.com>]

On Tue, 16 Apr 2002 16:36:32  
 Williams, Tim wrote:
>
>Steve Brusatte wrote:
>
>> Yes, Mike and David are correct here (AFAIK).  Monotremes do have
>> somewhat of a sprawling gait, as likely did multis.  

>I'm not contradicting you, and I know next to nothing about the finer points
>of mammal evolution.  But is it possible that the sprawling gait of modern
>monotremes is secondary and due to their specialized lifestyles.  The
>echidnas (_Zaglossus_, _Tachyglossus_) are fossorial and the platypus
>(_Ornithorhynchus_) is aquatic.  AFAIK, we don't have any postcrania from
>extinct non-tachyglossid, non-ornithorhynchid monotremes to know what kind
>of gait monotremes originally had.

Oh, feel free to contradict me if I say something wrong:-)  I'm no specialist 
when it comes to the finer points of mammalian evolution; I'm only going by 
what I've read.  That being said, Tim's above scenario is a possibility.  
However, if indeed multis are closer to placentals/marsupials than are 
monotremes, then it may be more likely that both multis and monotremes had a 
more primitive method of sprawling.  I know of no multituberculate fossil that 
shows an erect gait, although I could be very wrong here.

If we only had better fossils...

Steve

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