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Re: Vertebrae of Early Sauropods



Mike Taylor (mike@indexdata.com) wrote:

<The camellate condition is taken to the extreme in the vertebrae of
derived Titanosaurs such as _Saltasaurus_, in which the bone has
essentially the texture of a sponge, permeated by very many tiny bubbles. 
This is called the somphospondylous condition.  The same thing appears to
have evolved independently in _Mamenchisaurus_, so it may be a general
long-neck adaptation, and so less phylogenetically useful that it would
first appear.>

  Not to disagree with the premise here, but I would suggest that this not
be looked at so much as a long-necked adaptation, as titanosaurs typically
do not have very long necks, not so much longer than less than twice trunk
length, whereas diplodocids and "omeisaurids" have such a neck over twice,
and sometimes close to three-times, trunk length. Relatively
"short-necked" titanosaurids, like *Isisaurus colberti,* have
somphospondylous vertebrae, so this is a reasonable phylogenetic feature.
Titanosaur vertebrae are recognizable without this condition, as well.

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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