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Re: Feduccia (was: polarity of bipedality in dinosaurs)



Jonathan Wagner writes:

>>1. the similarities between birds and maniraptorian theropods are convergent
>        He's joking?

I quote from page viii, the preface:  "Nowhere has this trap [convergence]
been more successful than in luring palaeontologists to the theropod
dinosaurian origin of birds.  Theropods, with their bipedal gait and
foreshortened arms, superficially resemble flightless birds, especially the
ratites, through convergence....

"..... [after referring to the AMNH Dinosaur Halls] ..They, like many others
who adhere to a rigid cladistic methodology, have been led into that
perfidious trap of convergence that lies camouflaged and waiting for the
unsuspecting victim....

"The idea of a theropod origin of birds originally became coupled with the
idea, now largely disproven, of hot-bloodedness or endothermy in dinosaurs..."

And that's just the preface, folks.  I don't think he's joking.  My heart
sank when I read this, not because I am closed to his ideas but because he
seems to be declaring that the only really thorough book on avian
palaeontology available has no intention of taking an even-handed look at
the issues.  I hope I'll be proven wrong as I keep reading.

>>Feduccia makes much
>>of the comparative brain sizes of birds and maniraptors and ascribes this to
>>arboreality in the former [snip]
>        His evidence?

Again I haven't read very far yet, but on skipping ahead I find a section
(p. 121-124) called "Dinosaurs were "Pea-Brains"" (yes, really!).  His point
is that the only dinos with even ratite-sized brains, relatively speaking,
are late Cretaceous critters like Troodon, so their larger brain size can
have no bearing on bird evolution or you would have seen similar
developments in the earliest dinosaurs, such as Eoraptor, Herrerosaurus and
Coelophysis.  Of course he says nothing about the rate at which brain size
could have altered in an arboreal form,nor (unless I have missed it) does he
produce a non-dinosaurian Triassic archosaur with a birdlike brain.

>>Feduccia illustrates a hypothetical protobird on p. 92, as  long-bodied,
>>rather sinuous glider.  I find it hard to believe in such a creature, though
>>Feduccia seems convinced of it.  Am I missing something?
>        Yes, you are interested in paleontology, not ornithology.
>
>        Wagner
>+--------------------------------------------------------------------------+
>| Jonathan R. Wagner   

Actually that isn't quite right - my PhD is actually in ornithology!  In
fact I am writing a popular book on songbirds at the moment, and one of my
problems is what to say to a general audience about bird origins.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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