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Hey - there's a strange charm to your prose,
Headden: "While tyrannosaurs totally forgot they were more birdy than
*Coelophysis*, . ." . . has it ever been better put?!
While reading your 5th Aug "Flightless
Birds" piece, it all suddenly clicked for me - maybe because it could be
close to what you were saying. Are you ready for it? Right . . .
there now follows an account of my new position (except for viewers in Cladland
who have their own program). . .
Just recently, I have become totally and utterly
convinced that proper feathers *did not exist prior to _Archaeopteryx_* (or
something very close). _Sinosauropteryx_ was an important
clue. No flightless bird has ever been shown to have completely lost the
feather structure. Lost asymmetry - yes. Lost neat, ultra smooth low
drag contours, in exchange for long thin, and also "explosive" untidy
feathers giving a shaggy hairdo look? Yes. But never lost to the
extraordinary extent of _Sinosauropteryx_. Ratites, which have not flown
for something like 60 mill yrs or more still have proper feathers to some
extent. _Protarchaeopteryx_ & _Caudipteryx_ had feathers so good you
had to check the skeleton to see if they were flightless or not.
_Sino.._ would have had to have lost its
feathers a lot earlier than 60 mill yrs previously - and it couldn't have done
because of the post-Archae explosion which shows the effect the feather
revolution had. Pre Archae: absolutely no feathers found. Post
Archae: blam - it all happens. No. For me the proper feather was the
key to the birds' success and radiation more massive than most people
appreciate.
BUT -
. . . early dinos had some hollowed-out bones,
and progressively more robust thoraxes. They must have been doing
*something*. Clubbing their prey is a non-starter (sorry Kevin) since
[claws and "hands"] like that are totally unsuitable for heavy
strikes. Yet they couldn't have been flying either, since they only had
fur and usually no skin flaps. They must have been shinning up trees
(which encouraged strengthening arms and chest bones), and gliding/parachuting
on hair, maybe long, stiffened hair, growing from the arms, tail and possibly
elsewhere. At this point the peculiar backward-folding wrists might have
become useful, when trying to miss tree trunks.
That's it - now I'm happy. Predictions? No
feathers to appear pre-Archae; especially no feathers on _Coelophysis_,
_Protoavis_ or other such "too earlies". They all had fur like
_Sino..._ (...unless they were huge; some/most big dinos developed
scales).
Hair-for-gliding would have been incompatible with
cold-bloodedness. Warm-bloodedness, hair and gliding would have developed
together.
(As usual, I will not be answering objections of a cladistic
nature, which I regard as seriously flawed.)
Bits:
One good reason for dinos becoming steadily more
bird-like is that after extinction events, small forms are more likely to
survive, and tree-capable types are more likely to be small, which doesn't
require that birdliness is superior in any other way (though it may have
been).
Archie would have had little difficulty climbing
*up*; climbing down backwards might have been a different matter
though.
By the way chaps, a flightless modern bird with
useless arms and no teeth is a *totally different animal* to one with claws and
teeth; so much so that a great many comparisons of the type that are currently
being made are totally redundant.
Also, I do hope it's only a series of misprints
that is making at least three people say "secondarily flightlessness"
instead of "secondary flightlessness"!
John V Jackson jjackson@interalpha.co.uk
(Wannabeasaurus beecee-effia (sort
of) - & proud of it! )
"(contary to viewpoints expressed variously by Padian and Chiappe 1998, the claws of _Allosaurus_ and _Tyrannosaurus_ do not equate well with climbers). " That's reassuring!!
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