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>>Here's an alternative scenario:
>>Birds are the volant ancestors of nonflying coelurosaurs.
>What, have I converted you? :-)
Not necessarily. One can say that the dromeys and _Archaeopterix_ both have=
a common ancestor.
Here's another possibility: Archy is only known from Solnhofen sediments, no=
terrestrial ones. Now in a terrestrial sediment, only the toughest parts=
of the animal will survive (usually teeth, which are helpful if we're=
talking mammals, but a nightmare with reptiles). What if there were quite=
a few of these small theropods running around then; quite a few may have=
been arboreal too (yes, I have been convinced on this point;-). Now, just=
as with all the squirell (sp) species, there is only one (relatively)=
flying member. What if the dromey line evolved from one of the arboreal,=
non-flying, theropods. I still like the idea of the enlarged claw in this=
group used for climbing trees, and later exapted for a killing claw.
My biggest reservation for BCF is the unlikelyhood of the events. =
Essentially, what is being said is that an animal gains the power of=
flight, then gives it up again. What's the adaptive value in that??? I=
mean, no one talks about secondarily flightless pterosaurs. Once theropods=
learned to fly, a whole new set of niches opened up for exploitation, and=
it seems to me that the wouldn't be able to reverse the trend until the=
evolutionary momentum had run down. Evolution may be random usually; but=
once a trend has started, the group is usually committed to that trend to=