Re: dinosaur vs. bird locomotion

[Betty Cunningham <bettyc@flyinggoat.com>]

Kangaroo rats and humans at keast have the same muscles to move the rear
leg in locomotion; birds and dinosaurs or dinosaurs and humans do not.

One of the largest lomotor muscle in dinosaurs' hind legs is powered by
the tail, where it attaches.  Birds don't have it and neither do us
mammals.  So the hairy details of locomotion are vastly different.

BUT your prof coulda been a tad nicer and at least narrowed down the
bipedal/quadrepedal-ness of the animals in comparison.  Asking if a
Triceratops walks more like a chicken or a cow is, well, a little
different than asking if a T rex walks more like a chicken or a cow.  In
morphology.

-Betty Cunningham
(who HAD a pet chicken once that flew into a 40 foot redwood tree all
under her own power -of course it took her a day before she figured out
how to come back down. Petunia was never what we call a BRIGHT bird.)



Chris Noto wrote:
> Recently in my Intro to Paleo course my prof gave an example of theoretical
> morphological analysis using the "did dinosaurs walk more like birds or
> like mammals?" comparison.  What struck me is that it seems intrinsically
> flawed because birds are a highly derived form of one branch of the
> therepods and comparing them to, say, a ceretopsian would be like using a
> kangaroo rat as a comparison for human locomotion just because we're both
> mammals.  Furthermore, even using it as a comparison to non-avian therepods
> seemes a little off to me.  Aren't ground dwelling birds (like chickens)
> secondarily flightless and have a whole evolutionary history, setting them
> apart from their non-avian ancestors?  Then there's the size difference.
> No bird ever got that BIG, the scaling could throw it all off then.  You
> need to take into account the limits of the material used here (ie, bone).
> Could that affect certain proportions in limb length and throw off the
> analysis?  I've been thinking about this quite a bit and it just doesn't
> seem quite kosher, the differences seem to great.  Isn't that why birds are
> set apart from dinosaurs in the first place?  Any thoughts or comments
> would be appreciated.
> 
> thanks,
> Chris Noto


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