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Re: Lamarckian? (and some dromie specialization)
Christopher Srnka wrote:
<I would think it would more likely be a case of the ancestors of
deinonychus having a variety of physical configurations, and the ones
that had adaptations that best suited the animal's environment were
preserved, and the adaptations dictated behaviors; this explanation
makes more sense to me personally than to imagine that the DNA of the
ancestors of deinonychus somehow anticipated that longer, stronger
arms would better facilitate a hunting behavior.>
First, *Dromaeosaurus* has smaller pedal claws (especially the 2nd
digit one) than *Deinonychus*, while *Utahraptor* had comparatively
narrower claws, and *Velociraptor*'s were slightly straiter than all
three. Skullwise, dromaeosaurs were robustly skulled with large jaws
that were stronger than the flex-snouted velociraptorin theropods; or
so I would think from comparing them. This suggests that
*Dromaeosaurus* was more of a biter than a claw-attacker, thus arms
had really nothing to do with the animal; as for the smaller toothed,
bigger clawed forms, the arms were more significant, yet here the
reader beware: *Dromaeosaurus* appears in the Late K, while
*Deinonychus* is Early K, and *Velociraptor* is a comparatively
constratigraphic taxon with the first, yet all suggest exactly what
Now, on the subect of the facility of climbing in dromaeosaur arms,
comparatively, what is more advantageous? A smaller or larger deltopec
with an acromion, scapular blade, arc of movement and pull from point
A to B in either muscular system? Compared to ours, of course. Human
arms work best when the arm is totally strait, and the bones are built
this way. meanwhile, dromaeosaurids have larger olecranon (funny bone)
processes, deltopecs, longer scapular blade, an acromion, a better
stress "spring" system (the furcula) and shorter long bones compared
to each other, meaning less effort for any size muscle to achieve a
certain movement, and thus less energy required to do so.
Humans, to pull, do exactly what dromaeosaurids do: they pull the
humerus back and pull the ulna/radius in. Humans generally keep their
wrists strait, dromies apparantly had a pulley action that prevented
them from keeping the wrist strait while flexing the forearm. Dromies
seem more built to hold something to them and resist the force of a
struggling, pushing object, than one that usually doesn't; do you
usually wrap your arms around the object you want to contain, or not?
Dromies were just better at it. And dromies did appear better and
pulling towards themselves than did humans. Hunting, mating, swimming?
Maybe all three. Evolve something, there could be added benefits, wot?
-- I wonder if I went off the subject a little? :)
Jaime A. Headden
Qilong, the website, at:
All comments and criticisms are welcome!
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