Ralph W. Miller III <dinoguyralph@sbcglobal.net> wrote:
Needless to say, Philip Currie's analysis did not take account of
_Microraptor gui_, the "four-winged dinosaur" described in _Nature_ in
January 23, 2003. By the informal reasoning stated in the first line quoted
above, if this basal dromaeosaur could fly, then it may be considered (as) a
bird, even though its appearance in the Early Cretaceous precludes it from
qualifying as a theropod ancestor of Jurassic birds.
As Gregory S. Paul has noted, _Microraptor gui_ shares several features with
derived birds that are not evident on _Archaeopteryx_ specimens. The
_Nature_ article by Xu et al. puts forward the hypothesis that this animal
represents a gliding tetrapteryx stage from the dromaeosaur lineage that
ultimately gave rise to flying birds. Did it indeed glide, but not fly?
Could it not have done both?
Did the "four-winged" stage precede two winged animals, or are the "four-winged" theropods descended from theropods that sported only pectoral wings? There is probably no way of telling at this time.
Tim