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Re: Emus a Model for Dinosaurs?
So if the point of attachment of m.caudofemoralis along the length of
femoral shaft affects either speed or power of retraction depending upon
placement, what purpose does the trochanter itself serve other than more
surface area for muscle attachment or subtle change in leverage. . .
further, as Deinonychus and Velociraptor do share similar overall
morphology, what mechanical advantage is gained by the addition of a
trochanter in the smaller form?
Michael Skrepnick wrote-
Lack of a 4th trochanter would seem to be a far more overwhelming obstacle
to performing traditional bipedal theropod locomotion ( where then in fact
is the origin for a caudofemoral retractor in Caudipteryx? ) than the
alternative, a primitive knee driven movement supported by slender femora.
. . essentially, does a missing 4th + "convergent?" knee driven locomotion
trump the lack of a derived ( if even necessary? ) robust femor ?
The absence of a fourth trochanter in itself probably had little effect on
locomotion. Velociraptor's femur has a large fourth trochanter, for
instance, while that of Deinonychus lacks even a discernable scar. Yet
the genera are extremely similar in morphology otherwise, and Deinonychus
certainly lacks neornithine proportions.