Decoupling the Tail in Maniraptorans

["Jaime A. Headden" <qilongia@yahoo.com>]

Matt Bonnan wrote:

<The muscle we were discussing was the Caudofemoralis
longus.>

[snip]

<...However, maniraptoran dinos, especially the
deinonychosaurs and the like, have greatly reduced the
tail shelf and have almost no trace of the fourth 
trochanter. Furthermore, the tail in these dinos
becomes stiff and rigid. The idea is that perhaps the
tail began to be used as a rudder to help the animal
change directions more quickly with proper balance.
Because the C. longus muscle appears to have been
greatly reduced, the tail is essentially "decoupled"
from the hindlimb.>

  Not that I disagree, and thanks to Gatesy, I've been
able to catch some of these papers and have read
Gatsey and Dial and a Padian paper on biomechanics in
this area, but there's a middle-ground here not on the
direct path to birds, but as a side-line that went --
shall we say -- cukoo. Oviraptorosaurs (and
therizinosauroids, should they prove definitely to be
theropods of this mein) have perhaps the most
extensive series of caudals bearing transverse
processes and deep chevrons, but lack a fourth
trochanter. Is the _m. caudofemoralis longus_ coupling
the ovi tail and leg, despite the lack of a fourth
trochanter (though a pit is present), or is the
extensive shelving of the tail used for a different
purpose? Could each individual pair of transverse
processes link as a series of paired muscles (are
these the _m. iliocostalis_?) for extensive and
heightened flexibility -- flip the tail up, or
sideways, display those hypothetical feathers...?

  Heh, just a bit of speculation, but with a very
serious question behind it. Oh, to all interested in
my site, I will be revising those feathered and
colored page headers for the ovi taxa, given the more
cassowary-type dinofuzz apparent on *Sinornithosaurus*
(SIGN-or-nith-AH-sahr-us?). Either way, I'll have two
versions to play with. Can do a better *Conchoraptor*
and "Rinchenia," for instance.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.
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