Re: Paedomorphosis ( Re: BARYONYX' CLAWS )

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-04-09 21:34:53 EDT, m_troutman@hotmail.com writes:

<< Basically, the penguin, auk, and plotopterid "flippers" are 
 modified wings. They use their wings in a manner similiar to volant 
 birds. These birds still have a functional flight apparatus, but where 
 they are different from volant birds is in their forelimbs structure, 
 which is more robust. Penguins, auks, and plotopterids are essentially 
 still fliers, just in a water medium.>>

I wish you'd stop calling "swimming" flying. It doesn't help your argument a
bit. These are birds that have exapted their flight anatomy for the purpose of
swimming through water. In becoming more efficient swimmers, they lost the
ability to fly through the air. You noted in a previous post that there may
have been a transitional stage in which the wings were used both for flying
through the air and swimming through the water. With this I can agree.
Likewise with small, arboreal theropods, there was probably a stage in which
the forelimbs were used for grasping and climbing and for some kind of flying.
In later theropods, the grasping uses prevailed; in later birds, the flying
uses prevailed. Why is this incredibly simple, obvious, and natural idea so
difficult for you to accept?

<< Comparing these forelimbs to theropod forelimbs is an utterly different
comparison. Theropod forelimbs are lack many volant characteristics, whereas
penguins, auks, and plotopterids still retain these volant characteristics.>>

All you're saying here is that theropods would have made lousy swimmers (if
they tried to use their forelimbs for this). With this, I would probably
agree, too.

<< The basic theropod shoulder girdle is utterly different from the penguin,
auk, and 
 plotopterids. And the penguin, auk, and plotopterids still use the same 
 basic flying motions. >>

Of course the basic theropod shoulder girdle is different. The avian shoulder
girdle had not yet evolved when "basic theropods" (whatever those are)
diverged. The "basic theropod" ancestor probably used its wings for grasping
as well as for some kind of flying (certainly not powered, flapping flight,
but perhaps a kind of fluttering--better than nothing for those moments of
free fall when living in the trees).

You're making me ramble.