Neural Spine Crushing in Predator/Prey Grappling Behavior

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

I had written:

<<Dromaeosaurid dorsal neural spines are short, moreso cranially than
caudally, and robust rather than thin and blade like; they would have
good resistance to lateral bending forces, moreso cranially than
caudally. Additionally, the back musculature, as inferred from
vertebral processes, would have been robust enough to reduce the
lateral exposure of the dorsal spines in life; they would have been
about one-third buried in flesh, and almost invisible except for the
ridge posteriorly, almost unnoticeable anteriorly becuase of the
strong scapular musculature. It is then improbable that rolling would
have injured these animals' dorsal neural spines.>>

to which John Jackson replied:

<Why did birds develop more flexible necks (I presume this is what the
loss of overlapping cervical vertebral processes means)? Preening
requirements?

Maybe the "squared-off ribs at the rear of droms and troods" would help
here too.>

  This is true. The posterior dorsal ribs (I assume this is what you
mean) are ventrally directed with horizontal transverse processes,
with the added effect of making the dorsal and anterior hind limb
musculature more rigidly anchored. The opposite with the anterior
dorsal ribs, where the ribs could, in fact rotate slightly, and were
more posteroventrally directed, and would have had some flexing in-
and outwardly to aid scapular and cervical musculature, and rotation
of the scapula. Or at least as I had seen and read. The posteriormost
dorsals were associatedly rigid, the anterior ones with greater
flexibility. The benefit for droms? Stronger fore/aft movement of the
humerus, I can see right now.

Betty wrote:

<<<when I roll on the ground my vertebrae do not break. Horses
out-weigh me by as much as 10 times and they don't break vertebrae
when they roll either (they scratch this way).>>>

I wrote:

<<In both humans and horses the neural spines are buried medially
between the rib heads, and for the most part are not exposed laterally
in horses except towards the flanks and withers, and this was covered
in huge masses of muscle, and in humans they are not exposed at all
except in the anteriormost dorsals (thoracic) and cervicals, so the
risk is negligible.>>

Rich Travsky wrote:

<I should have left more of the original context in.

Not mere rolling on the ground, I had more in mind the image of the
predator hanging onto its prey, and both rolling together. That's a lot
of weight and momentum, esp with big prey.>

Pat Norton wrote:

<It seems to me that what you're seeking is fossil evidence of a
fundamentally maladaptive behavior. Neural spines that break during the
struggle for food would not be an enduring evolutionary characteristic.>

  Additionally, the animal's bodies would have been crushed under the
weight of the lunch in question; since this all started with the
Oklahoma specimens of *Deinonuchus* (*Velociraptor*) and
*Tenontosaurus*, I'll use those as the models, and warmly turn
everyone to Ostrom (1970) and Paul (1988) who have commented on length
of the association.

==
- Often, it is the man who is brought
  down the path to the end who does
  not see his own steps. -

Jaime A. Headden

Qilong, the website, at:
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