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RE: Bakker & whiptails - jog my memory please!
One of my questions regarding the supersonic sauropod tails regards the
fraying you see in a bullwhip. The tip of a bullwhip travels so fast it
breaks the sound barrier, true, but because it cracks so fast, the ends
of the whip eventually begin to fray. Not only that, but a bullwhip is a
continuous piece of material. <<<
The continuity of material is an interesting question. Of course,
bullwhip continuity is really a matter of scale. The tissue that makes up
the bullwhip is made of different layers, as well as individual cells. I
bring this up, not because I think tht this data influences bullwhip motion,
but because sauropod tails are so much larger. So from a mechanical point
of view, those huge sauropod verts are going to be smaller in the context of
a butt-whip. I'm not sure (and I don't think anybody's sure) what the
maximum size is that individual mechanical units can have while still
funtioning as a whip, although the study done by our fellow lister did
simulate the length and inferred mobility of each vertebrae, so that's a
start. Estimating mass and required muscle/tendon strength would provide
some limits on what cannot be done with animal tissue. Masters project,
As for the frayed whip end. This isn't just a sternght of materials
problem, because that fraying is actually intergral to releasing energy (in
terms of sound) when the end breaks the sound barrier. Basically, the
difference between a non-frayed and frayed tail is the difference between a
loud pop and a theropod-ear-melting boom. Because of the behavior of dermal
tissue upon damage, Ken Crpenter doesn't think sauropod tails could break
the sound barrier (as presented in Eggs, Nests, and Baby Dinosaurs).
However, in at least some diplodocids, there appears to be a row of "spiny
things." I don't believe that any histological evidence was preserved, but
my best guess is that they were keratin.
And to conclude briefly (hah!), if keratin was already present in
sauropod caudal dermal evolution, then I see know particular barrier to
evolving a softish continually growing tuft on the end of the tail. This
is, of course, speculation, but at least there is no biological barrier to
sauropods evolving a "popper," should the biomechanics end up consistent
with a supersonic whip.
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