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RE: titanosaurs



On coding vertebrae as seperate components:

  The problem with this obviously is in the ten or so vertebrae all
sauropods share in the cervicodorsal sequence which are either uniquely
duplicated or transformed from one series to the other. Post-axial
cervicals in bifurcate-spined cervicals are cohesive through the dorsal
series, so at which point does the 15th postaxial with bifidy conform
between species if in *Mamenchisaurus* it is a duplicated vertebrae (say)
while in *Diplodocus* it is a transformed dorsal? It is obvious in
sauropod evolution that aquired cervicals and duplicated elements remain a
main problem in determining similarities in the sequences. For instance,
while it is clear omeisaurs have duplicated cervical elements based on
gross presacral vertebral count, I doubt it is clear which elements are
duplicated, and this is where the "cervical 15 bifid or not" does not play
out as it may not carry an phylogenetic signal, whatever the cladistic
matrix suggests when run for parsimony and heurism.

  Applied in other areas includes tooth counts in some ornithischians,
birds, or spinosaurs, where the primitve animal generalizes lower numbers
than advanced forms, indicating an increase during evolution that must
occur by duplicate budding. Thus, application of element number between
species is not consistent, and should not be used as consistent and
therefore phylogenetically significant.

  Cheers,

=====
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.

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