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Re: Sphenochians and birds
Jean-michel BENOIT" <Jean-Michel.BENOIT@gemplus.com> writes:
I was re-reading recently a _quite_ old but interesting book written by the
Cserkases with help from Olson. It spoke of a possible origin of birds
within the sphenosuchians,
This theory (which walker supported for a time) is now widely discredited.
Sphenosuchians like Terrestrisuchus (which you mention) are basal
the fossil called *protoavis*, having elongated forelimbs thus thought to
have had a arboricole ( is this the correct word? ) life but found with no
evidence of feathers.
Protoavis is thought by Chatterjee to possibly arboreal and undoubtedly
volant (i.e. able to fly). The idea that Protoavis is a bird has received
very little support in the paleontological community. The true identity of
Protoavis is still uncertain - it may be made up of bones from more than one
It was thought to be derived from animals like *terretrisuchus* placing the
first bird-like reptiles back to the triassic period.
Even Chatterjee believes birds to have evolved from dinosaurs, not
The text said that embryology showed that the missing fingers in birds were
not the same as in theropods but were the same to those of crocodilians.
This is probably not correct. Certain opponents of the birds-from-dinosaurs
theory claim that the homology of the fingers differs betewwn theropods and
birds (I-II-III vs II-III-IV). The embryological basis for this in birds is
controversial, but I think it's fair to say that the embryological evidence
is reconcilable with the I-II-III origin of the digits in birds (as in
theropods). There are some recent papers which discuss this.
I'm not very sure I've understood all the scientific explanations but it
seemed very convincing to me. How about this theory? Is it still debated or
has it been abandonned for ever?
It has been largely abandoned, but never say forever!
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