yes, it's a very complex picture, expecially since microraptor lived some 20 million years
after archaeopteryx.
quote:
Longrich speculates that the hindlimb feathers might have served other roles in addition to flight. Like modern pigeons, kittiwakes and vultures, Archaeopteryx's hindlimb feathers might have acted as airbrakes, or perhaps stabilizers, control surfaces or flaps, Longrich writes.
(from the article linked above)
i think that function is probably more likely, especially for archaeopteryx.
quote:
Scientists don’t know when in their evolutionary history birds switched from a "four winged" design to a two-wing one, but it's thought that hindlimb wings were sacrificed in order to free up legs for other functions, such as running, swimming and catching prey.
there's an interesting idea that's looking more and more valid all the time -- that the idea of "fling birds" and "running dinosaurs" are a bit more convuluted than previously thought. meaning that early dinosaurs took to the air far sooner than previously thought, and subsequently lost flight capabalities, only to re-evolve them.
there are many things we are calling "birds" that have a good number of dinosaurian characteristics that archaeopteryx lacks, and vice-versa. as suggested earlier in this thread, it's quite possible that some of the especially avian maniraptorian dinosaurs might have actually evolved from something like archaeopteryx. so it might be right to call velociraptor a flightless bird, under the current thought. essentially meaning that our current colloquial usage of "bird" describes a polyphyletic group, composed of many groups that independently evolved from the dinosaurian line. it would certainly explain the "opposite birds."