Re: Paedomorphosis ( Re: BARYONYX' CLAWS )

["Matthew Troutman" <m_troutman@hotmail.com>]

>> I don't believe in the cursorial origin of flight either. But you  
ignore >>that flight may have evolved from animals that exapted certain 
>>features of climbing and gliding.

<<Climbing and gliding are integral parts of the BCF scenario, do not 
forget. So is aerodynamically controlled leaping between branches, 
squirrel-like. I consider aerodynamically controlled leaping and gliding 
to be primitive forms of flying, of the kind that eventually developed 
into the powered, flapping flight of modern birds. Even falling--as long 
as it is not accidental but is part of an acronomic (acronomic: my term 
for "dwelling in high places," such as trees, cliffs, etc.) animal's 
lifestyle--can be considered flying, albeit the most primitive kind of 
flying of all.>>

     Well, if you define it that way... a person's terminology is 
different from an another person's. Controlled leaping is seen in 
kangaroos, kangaroo rats, grasshoppers, monkeys, and other creatures, 
not your typical fliers. I call arboreal gliding; arboreal gliding and 
flapping flight; flight.

<<So, for example, let's say an animal lives in the trees and makes its 
living by falling from tree branches to capture prey. If it gives rise 
to a descendant form that lives on the ground and abandons the ancestral 
arboreal "falling lifestyle," I would consider the descendant form to be 
secondarily flightless. This is not as peculiar as it might at first 
seem; but in any case, I'm just defining my terms here to avoid later 
confusion.>>

     If some coelurosaurs did have arboreal roots ( dromaeosaurs ) then 
they can be considered secondarily flightless in this sense. However, 
roadrunners went from an arboreal to a teresstrial existence and I doubt 
you would say they are secondarily flightless. 

The form of secondary flightless that I argue against is the flightless 
is the one where some theropods had volant ancestors that went 
flightless. Since they lack the paedomorphic trends seen in birds, it 
seems unlikely that they had volant ancestors. I think that we have come 
to an understanding ( at least it seems so ). I think that it sounds 
that you you agree that no theropods had volant ancestors ( at least it 
sounds like that ) because they lack the paedomorphic trends see in 
flightless birds. 

By the way, I find this discussion one of the best I have had since I 
have joined the list in August '97. For everybody who had a part in it 
so far: thanks.

MattTroutman

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