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Re[2]: Amargasaurus

     Hello Matt,
     I think that some Australian lizard species do have a
     fatty deposit in their tails. In particular some species
     of Gecko and one particular species of Skink known as the
     Shingle Back.
     Doesn't the Chuckwalla (I think that's the common name), a medium 
     sized lizard from the (SW) arid regions of the US & Mexico, have a
     similar adaptation?
     Miguel A. Garcia

______________________________ Reply Separator _________________________________
Subject: Re: Amargasaurus 
Author:  <mbonnan@hotmail.com> at mailgate
Date:    30/11/99 22:27

Dinochandler said:
>have neural projections similar to that of _Ouranosaurus_ and _Spinosaurus_ 
>and they have humps, not sails.
And went on further to say that the humps were potentially fatty and stored 
energy, etc., like bison (and camels I presume).  The reference does not 
come immediately to mind, but it was published in the journal of 
paleontology if I recall correctly.  My problem with this idea was that the 
large neural spines of a bison are supporting large muscles and the nuchal 
ligament for their big heads.  Camels, which have very large humps, do not 
have very large neural spines.  Can we infer a fatty hump from tall neural 
spines?  What's up with spinosaurs, then, or for that matter Dimetrodon and 
other pelycosaurs?  I'm not sure I'm convinced.  As both animals used as 
analogs here are mammals, that makes me more leary.  Perhaps mammals in 
desert climes are developing these fatty humps for energy and water storage 
in part because they excrete urea.  They lose more water than a reptile or 
bird, which excretes uric acid, a much more water conservative fluid/paste.  
As dinosaurs probably excreted uric acid, the need for a water-storage hump 
seems less likely.  I cannot think of a bird or reptile with fatty storage 
sacs/humps, but if those of you out there can, please post to the list.
Matt Bonnan
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