Re: What is a Dinosaur? and semilunate carpal

[Dinogeorge@aol.com]

In a message dated 9/6/01 2:19:06 PM EST, aspidel@infonie.be writes:

<< Or could we say that more stable hands were more efficient for a predator,
 and that this feature was selected in the evolution of flight?
 
 In other words, what came first: evolution of flight, or selection for
 predation? >>

That's something like saying, "Well, either there's life on Mars or there 
isn't. So the chance of there being life on Mars is 50-50." Either "stable 
hands" developed for flight or not; it's 50-50.

So this is where the Big Picture comes in. As I've mentioned here before, 
fossils don't come with little signs on their features stating, "I am 
evolving toward flight" or "I am evolving from flight." We have to examine 
the fossils and fit a theory to them that accounts for their features. 
"Stable hands" are certainly not required for predation--they are probably a 
>hindrance< to predation--otherwise there would be more predators with 
"stable hands." But "stable wings" >are< required for the kind of flying that 
birds do; it would be positively selected for in the evolution of arboreal 
dinosaurs, and all modern flying birds retain them. So it is more likely that 
"stable wings" would develop for flying and then would become exapted by a 
flightless predatory descendant than that "stable hands" would develop for 
predation in a flightless predator and then would become exapted for flight.

In the standard theory of avian flight, "stable hands" is one of those 
characters that arose by chance in predatory dinosaurs and then miraculously 
found a use, along with all those other characters that also arose by chance 
for various other reasons, in flying. Sorry, I don't buy it (and in fact I 
think it is ridiculous), >especially< since there is a very straightforward, 
reasonable explanation that doesn't involve any more random chance than 
necessary for theropod "stable hands" in BCF.