Re: Ancestors and descendants (story for Nick)

["Timothy Williams" <twilliams_alpha@hotmail.com>]

Jeffrey Martz wrote:

> Is the weight-bearing front foot of a Diplodocus any less
> different from the clawed theropod hand then the flying forelimb of a bird?
> Birds might be impressively diverse and specialized fliers, but I would
> hesistate to say they are really any more derived from the little meat
> eating runner design then sauropods or Ornithischians.

All spot on!  However, the implicit and overriding theme of the Kinman-ian 
scheme is PROGRESS!  Because of their warm-blooded-ness and the profound 
anatomical innovations (in the musculature and skeleton) that birds 
underwent in order to achieve powered flight, the birds deserve their own 
"Class" among the vertebrates.  We see birds soaring over our heads, but not 
(fingers crossed) _Diplodocus_.  You and I may believe that birds are just 
flying theropods.  To the Kinman way of thinking, birds have moved UP the 
evolutionary ladder and have graduated to a Class of their own.  I can't 
imagine a dissection of _Deinonychus_ would reveal all that much different 
to _Archaeopteryx_,  but the latter makes the cut into Class Aves, 
_Deinonychus_ doesn't.

Mammals also get their own Class because, like birds, they are also blessed 
with warm-blooded-ness.  The classes Aves and Mammals were principally 
formulated for this reason.

By the same peculiar reasoning, the vast array of basal archosauromorphs and 
basal archosaurs all get dumped into the "Thecodontiformes" - a polyglot 
wastebasket including rhynchosaurs, champsosaurs, poposaurs, phytosaurs, 
ornithosuchids, etc etc.

The Kinman-ian system doesn't make an iota of sense to me.  As I said, it 
combines the worst aspects of hierarchial and cladistic methods.


Tim

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