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Re: The life of birds



I wrote:

<<I do kinda like the ground up theory in which the ancestral
dinosaur, (oh, say, *Eoraptor*; we'll call it a "whatever" for now,
pending Holtz and Padian) scrambled up trees to get at bugs and flying
lizards, with perfectly adapted wrists, and spawning the terrestrial
lineage that kept that multi-task function of the hand, and later
spawned birds, who adapted (okay, exapted) the wrist to fly. Birds are
spawned by arboreal "whatevers", and terrestrial theropods arose from
arboreal "whatevers". Thus birds were both ground-up and trees-down,
but that's just one possible take on things.>>

John V. Jackson wrote:

<I like that theory too, though I'm not sure I think the name "ground
up" is quite right for it! I realise one of your "whatevers" came out
as arboreal when it probably should have been terrestrial,>

  Hmm, which one?

<but the question still remains, why did the whatevers take from
Eoraptor to the Tithonian before suddenly enlarging the hand?>

  I think pneumatic vertebrae, hollow bones, elongate forearms
(moderate, anyway) a more tridactyle pes with a hallux that could
conceivably orient against or with the other toes, a tail that was
distally stiff, inter-cranial kinesis, an enlarged cerebelum for
processing the predator-things that predators do, and I'm sure one or
another things. I've not done a whole lot of work on this part, but so
far, this is what I see. Once I get a more comprehensive sample and
analysis (more or someone else's) of the Triassic/Jurassic Theropoda,
I can gague better the changes. Holtz (1994b) offers plenty of data on
changes from *Coelophysis* to *Archaeopteryx* and *Ornithomimus*, so
that might be a logical place to start.

  However, it comes to an odd point that may or may not be true:
dinosaurs are not bird-like: birds are theropod-like. This is, of
course, assuming birds _are_ dinosaurs. :)

  Food for thought....

==
Jaime A. Headden

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

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