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Re: Dromaeosaur climbing & propulsive abilities (was Re: Jurassic Park 4 Script Review)



From: "Amtoine Grant" <ajgrant@eastlink.ca>  writes:

> On that, has it been proven that the hind legs were held in a
> horizontal plane as Microraptor is often pictured?

On this very list, some have claimed such a position would dislocate the
legs, while others have written that _Microraptor_ had unusually flexible
hip joints (though not necessarily sufficient to support both legs in a
horizontal plane), and others are withholding judgement until further
studies and specimens provide more information.  The archives are endless -- 
profit by their wisdom, or ignore them at your peril.

> Or perhaps even
> which direction the feathers pointed?

The orientation reportedly differs somewhat between specimens.  Whether this
reflects the variety of positions the living animal assumed or taphonomic
mischief is a good question.  Probably a mix of the two.

> > It _would_ be nice to get full fluff, complete with tail fans and
> > wings on the JP 'raptors.

Hear!  Hear!  But rather late in the series unless they are presented as a
"new, improved" generation of raptors.  Or maybe we can hope for "special
editions" of all of the films, with integument and every other gaffe fixed.
As if!

> Hold on, goats can climb trees?! Mountain edges & cliffs are one thing,
> but trees?

Yes.  Goats can climb trees.  See
http://www.davidhaberlah.de/galleries/redsea/pages/rs_04.html.  C'mon,
folks, do a "google images" search before you assume that it's impossible!

> Has anyone done any comparisons between dromaeosaur hindlimbs &
> kangaroos, the quintessential 'hoppers' of our day?

I seriously doubt that this is an apt comparison.  On the other hand, my
understanding (and please correct me if I am wrong)is that dromaeosaur
hindlimbs and tails would be well suited for leaping and kicking, though not
in the style of bounding kangaroos.

> Besides launching
> from trees or a running start, hopping/leaping is the next logical
> precursor to wanting to increase hangtime. Which brings me back to my
> first point on spring-loaded toe claws. Given that they're pretty round
> in cross section and less made for slicing, it may be a possibility
> that may have used them to sort of anchor, then using the spring loaded
> action(lol, G.I. Joe) used them to slingshot themselves forward. Only
> they couldn't do this on rocks. They could off a branch though. . .

Oh, my.  We do seem to be conflating our functional morphology speculations
with cartoon actions.  And no, sickle claws (known to us by their bony
cores, I hasten to add) are not round in cross-section.  For the most part
they resemble nothing so much as cat claws, and they may have been much
sharper in living dromaeosaurs with the keratin sheaths intact.

And wouldn't the claws hook into a branch just when the dromaeosaurs
attempted to launch themselves forward?  Sounds like a Wile E. Coyote move
to me!  Not that I'd put it past the capabilities of "smarter than chimps"
"fast as cheetahs" movie raptors.  Those guys can do anything the
scriptwriter tells them.

--------
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology