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CAUDO-FEMORALIS REMODELING



Mark Shelly wrote:
<<    In summary, it would appear that a rear facing pubis and development of
the ?drumstick? muscles may also have allowed the reduction (possibly for
weight reduction) of the caudi-femoralis.  Theropods with rear facing
pubes, relatively shorter femurs, and thinner tails may have had flying
ancestors.
     These are the only other biomechanical reasons I could come up with,
are there others that I am missing? >>

Actually, it is quite probable that the elongation of the
tibiotarsus/shortening of the femur and the enlargement of the calf muscles
is directly related to the retroversion of the pubes and lightening of the
tail in dromaeosaurs and birds.

A probable explanation for this is that when small, basal maniraptorans were
climbing around in the trees, they got the 90 degree tail bend trick which
also lightened their tails, which necesitated the retroversion of the pubes
for proper balance.  When this happened, the caudo-femoralis, which in dinos
was the MAJOR leg mover, lost most of its attachment area, so to compensate
birds etc elongated the tarsometatarsus and enlarged their calf muscles.

This is also an explanation as to why big quadrupedal dinos never lost their
big tails.  There is no real reason sauropods needed long tails for balance
or whatever.  They did need them to anchor their leg muscles though, and
there was no real reason to change to the calf dominent bird style, since the
tails of sauropods didn't get in the way like they would in the branches of a
tree.

Peter Buchholz
Tetanurae@aol.com

The fact that it recorded static is not what I find interesting, the fact
that it recorded approximately 18 hours of static is.