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Re: Pterosaurs and ABSRD (sensu Williams)



I wrote 

>
>  If Dave Peters is right and Longisquama and Sharovipteryx are also derived
> prolacertiforms then ABSRD has another problem. Feduccia wrote in his "The
> Origin and Evolution of Birds" that Longisquama, Scleromuchlus and
> Megalancosaurus were a disparate group of "avimorph archosaurs" from which
> birds are descended. In "Nonavian Feathers in a Late Triassic Archosaur"
> (Nature 2000, vol. 288) Longisquama's integumentary appendages were
> interpreted as nonavian feathers propably homologous with avian feathers. So
> now it's nonavian feathers in a non Archosaur.
>

Luis Rey answered

>
> That IS the problem... who the hell can confuse Longisquama scales or
> structures' with feathers? They are not only not homologous with feathers 
but
> have no similiraty whatsoever with any known feather (that unless we still 
have
> the caricature of a feather in our heads or you consider insect wings or 
fern
> fronds like good analogies for feathers). There's no real branching 
whatsoever
> and there's a hollow ridge all around it. Should be clear by now that this 
is
> not any evolutionary step towards a true feather.
>

Should have renamed "Nonavian Feathers in a Late Triassic Archosaur" into 
"Non-avian Non-Feathers in a Late Triassic Non-Archosaur" ;-).

But I concentrated on the fact that Longisquama as kind of a chief witness 
for ABSRD isn't even an archosaur as claimed by Feduccia, Ruben, Geist and 
Martin. So if Longisquama would be a possible ancestor for birds it would 
make birds also derived prolacertiforms. Thus making birds and pterosaurs 
sister taxons!!!

So Longisquama will be a problem (for ABSRD proponents) because they say to 
have found nonavian feathers, but now outside Archosauria.

Regarding the question of these appendages in Longisquama,  I really hope 
that these are some kind of integumentary structures. But I don't think that 
these are feathers. As Luis Rey wrote there's no real branching in them. Just 
compare it with the integument of the new feathered theropod.

Cheers


Heinz Peter Bredow