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Re: Status of _Caudipteryx_
In a message dated 12/30/00 1:39:32 AM, firstname.lastname@example.org writes:
<< As a statement of evolution, one cannot say something is primtiive
without an evolutionary sequence that demonstrates transformation or
acquisition. Also, it would not be recommendable to assume a state that
an animal is not at, such as colugos (flying lemurs) being somehow
primitively flightless because for some reason a related group of
mammals became flighted. Huh? What does this say about the colugos? It
means nothing about flight except that it does not fly, like a relative
does. Supposedly bats and colugos are each others closest relatives, or
megachiropterans and colugosa (Volantia). It is not "primitively
flightless," it is flightless, full-stop. >>
Well, it isn't EXACTLY "flightless, full-stop,"(it can glide, which is sort
of flying) but that's not the point at all. Caudipteryx and some of it's
contemporaries may NOT be "secondarily" flightless, but be the evolutionary
equivilent of the colugo as compared to the fruit bat. The critters of the
time we're talking about were more diverse than we currently know about.
Think of these things like hipperions. The evolution of the horse was indeed
linnear from Hyracatherium to Equus, however there were lots and lots of side
branches like hyperions which didn't make it to the present day.
<<I'm sorry, but in an evolutionary scenario, you can know an end
product, only in the present sense. We could be primitively aquatic,
but you wouldn't say this unless you _knew_ of a product that became
aquatic that stemmed from _us_. You going to tell me that whales are
primitively flightless? At some point, any organism _can_ be
flightless, but I've already expounded on _a posteriori_ statements.>>
The chemical evidence shows that colugos are closer to fruit bats than to
anything else, and are thus a good model for what we are talking about. A
whale doesn't have any of the equipment to evolve flight, like say, a flying
squirrel, and a colugo does.
You've got two closely related branches, one learned to fly and one still
glides, the latter is "primitively" flightless. A cat or a whale, not having
any adaptaions for flight whatsoever, are out of the picture entirely.
So we've got lots of birds and 'bird-oids' in China and whether they are
primarily or secondarily flightless is currently unknown.