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Re: Eustreptospondylus Q's



I wrote:

<< Number two, the animal had a longer tibia than a femur, and a
pretty slender metatarsus, showing that it had the ability to run
better than some of the even bigger fellows that were around, and much
better than oviraptorosaurs, let me tell you. Similar to some
tyrannosaurid and troodontid leg proportions, in fact, as well as
allosaurids. The ilium bone of the hip was pretty long, but not
particularly, and tall, similar to *Coelophysis* and *Marshosaurus*,
suggesting a strong iliofemoralis muscle, which would have stabilized
the leg in a forward lunge and helped draw up the femur better than
more primitive ilia (like coelophysids) show. Yeah, it was a runner.>>
 
<Some animals are sprinters while others are up to a long chase. Are
there physical characteristics which would make it possible to
distinguish between the two types of runner? Your reference to a
'lunge' might indicate that it is possible.  Thanks.>

  The difference between a sprinter and a long-distance runner might
be to take a comparative look between the leg anatomy of cheetahs
(*Acionyx* and various gazelles (*Gazella*); you may notice that
cheetahs run like normal little cats, just a whole lot faster -- their
muscles are narrower, and longer, providing more strength for their
use; gazelles too, but where the antelope differ is in the bony
structure of the ankle and various positions of muscles and tendons,
largely acting as braces, and in the particular way they run (ie,
mode, or gait). I'll not go into detail, and biomechanics ain't my
best subject to deal with, but I need to do this study anyway.

  Cheetahs run faster, but gazelles hop; special nasal and respirtory
and heart adaptations allow the gazelle to conserve heat as it runs,
and specializations in the skeleton, tendons, and musculature allows
it more bang for its buck. This is normally how a rabbit can outrun a
fox or lynx (occasionally) as well as the shorter body allows it a
much better turning radius that flexible backed carnivores lack. But I
digress (this is not the Mammal List, after all :) ).

  The lunge I mentioned earlier is merely the muscle pulling tight on
the femur, propelling the animal forward in a quick "dart" or "lunge".
All animals possess this. Now, someone may help me by pointing out how
the sprinter's "lunge" differs from a normal running gait, but from
what I understand of Olympic sprinters and runners and studies
thereon, there really is none: a sprinter starts from a dead stop or
slower pace and immediately accelerates into a specific rate of speed
higher than the typical run; typical runners, on the other hand,
accelerate more or less gradually. Horses can sprint, but I'd think of
them more as gradualists, dealing with their size and mass by
developing distinctive gaits that hand their bulk at different speeds.

  Anyway, this has gone on long enough (my comments on mammals, that
is, not the thread), and is getting close to off-topicness. I think
the Archives have some of this info, but am unsure: the search engine
there is bunk right now. For comments not dino-related, could we talk
off-list?

==
Jaime A. Headden

Qilong, the website, at:
http://members.tripod.com/~Qilong/qilong.html
---
All comments and criticisms are welcome!

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