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Re: Kickboxing Cassowary



----- Original Message ----- From: "Augusto Haro" <augustoharo@gmail.com>
Sent: Thursday, October 02, 2008 2:00 AM


I might say I do not know after all whether you "slashists" or we
"stabbists" are right. However, I lean to the latter interpretation because
some lines tend to give me there:


a)-gracility of the jaw musculature and small teeth in Deinonychus and
Velociraptor do not suggest large prey consumption (however inconclusive
seeing *Varanus*).

These features suggest that the jaws & teeth were not used to kill large prey (*Varanus*, being venomous, cheats). They do, however, suggest that prey was _eaten_ that was too large to be swallowed whole or ripped to pieces.


b)-gracility of the forelimb, and likely weak musculature, as to hang from
large prey (compare with megafauna killers such as *Smilodon* or lions).

Cats, especially sabertooths, have extremely strong forelimbs for holding prey in place when the bite is being done (saber teeth were likely too fragile to be used on struggling prey, and as we're talking about mammals here, they weren't replaced). Dromaeosaurid forelimbs are adapted for maximum speed of movement -- perhaps stabbing movements using the large finger claws, or holding the prey just long enough for a kick.


c)-general body gracility, basically because of the thin-walled bones, which
are indeed weaker than thicker walled bones (their apparent strenght via
reinforcing bars is really a way of not to lose so much strenght while the
cortical part of the bone is thinned).

The limb bones were not pneumatic, and eagles can do quite some wrestling despite having almost completely pneumatic skeletons.


d)-lack of enlargements of origins of limb muscles (gastrocnemius,
long/short digital flexors) to give the sufficient strenght to perform
cuttings, which are otherwise poorly used in nature, and seemingly require
more force than stabbing, except for superficial cat-like scratches.

Are you sure about this lack? *Achillobator* is named for having a tendon attachment site on its sickle claws that is as large as the one for the Achilles tendon in other tetrapods.


-Why is the neck of the sabertooth so muscular if great musculature is
not necessary to not only stab large prey, but also for slashing, what the
sabertooth likely does not do??.

I do think it did that. Why else is the cutting edge serrated?

e)-thickness of the claw makes it more difficult to sunk the claw and at the
same time making the cut than when using, say, a Ghurkha dagger.

Is it that thick?

f)-general inferiority of keratin and bone materials when compared with
steel.

That doesn't mean they aren't still good enough.

g)-lack of analogues for that behavior (i.e., large prey-killing) in extant
outgroups (EPB), and lack of use of unguals for slashing in general along
Vertebrata.

The lack of sickle claws anywhere outside Deinonychosauria makes all of this pointless.


h)-differently from mammals, in the flanks of the abdomen in herbivorous
dinosaurs there are ribs, that should have pointed posteroventrally, thus
making it difficult to cut through that region.

Not that much, especially in ornithischians. Also, what about cutting the leg muscles to immobilize, rather than kill, the prey?


For large prey killing and consumption, the greater size of teeth
and mandibular adductors in Dromaeosaurus might be better testament.

*Dromaeosaurus* seems to have used the tyrannosaur method: attack by strong bite. This method is probably more limited by the size of the predator than generally slashing methods (including the hacksaw method of *Allosaurus*) are.


Other thing: in "Jurassic Fight Club" we see an Allosaurus hopping and
delivering kicks to a sauropod: it seems unlikely such a large animal was
capable of jumping to kick.

Not really. However, it is unlikely that it was able to jump high enough. (I haven't seen JFC, though.)


Jumping height is proportional to leg length (proportional to body length), proportional to muscle cross-sectional area (proportional to square of body length), and inversely proportional to body weight (proportional to cube of body length). All else being equal, it is therefore independent of body size. Elephants can't jump for the same reason turtles can't jump -- they're graviportal --, not because they're too large.