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Re: Peering at review



In a message dated 10/21/02 3:17:17 PM EST, TiJaWi@agron.iastate.edu writes:

<< Yeah, OK.  But I think the reason why paleontologists take issue with the
 BCF scenario is that there is absolutely no evidence for it.  Tree-dwelling
 basal dinosaurs that looked more like modern birds than _Archaeopteryx_ or
 _Microraptor_ did?  It's a nice story; but there isn't a shred of evidence
 in support of it. >>

No, tree-dwelling dinosaurs that looked something like Archaeopteryx but were 
not quite as flightworthy. Nowhere do I say that birds of a >modern< aspect 
necessarily existed prior to Archaeopteryx (although they could have--it 
wouldn't hurt). For the common ancestor of, say, Allosaurus and modern birds, 
try to imagine a small, feathered Microraptor-size tetanurine predator with 
unfused-three-fingered wings (and furcula). It would have lived during the 
Late Triassic or Early Jurassic; its skull would have been considerably less 
derived and much more theropod-looking than that of Archaeopteryx; it would 
have had a long, feathered tail and it probably wouldn't have been a very 
good flier, just a flutterer or parachutist. Etc., etc. Not at all a 
modern-looking bird. We haven't yet found fossils of anything like this kind 
of animal, but more importantly we haven't found >any undoubed fossils 
whatsoever< of pre-Archaeopteryx dinosaurs. There is a great missing-link gap 
here due to the small size and delicate nature of such animals. Unless you 
believe in the special creation of Archaeopteryx, of course.