RE: Limbs and niche partitioning

[rjmeyer@ix.netcom.com (Rob Meyerson)]

Pat Norton writes,

>One niche that opened up was the aquatic environment.(snip)  I   
>wondered about this as I thought about Sinornithosaurus, which apparently   
>couldn't fly but had integumentary fibers of some sort and a shoulder   
>girdle capable of a flapping motion.  As I said, wildly speculative.

You have a plausible idea, but here is a thought to ruminate:

How does the evolution of flight feathers fit in with this?  In water, it seems 
that the selection pressure is to evolve smaller, waterproof feathers.  Now, 
consider the in-between phase.  How does a waterbird go to an arialbird?  We 
seem to need a landlubber mode (another aboreal phase?) to allow the flight 
feathers to evolve.

Overall, we may be making things too complex in the absence of definate 
fossils.  It sounds as though we are needing too many habitat changes to evolve 
a flying bird from a dinosaur ("all things being equal, the simplest answer is 
usually the correct one").  Perhaps we need to take a step back and reexamine 
this issue from a wider angle, and develop our hypotheses in a way that 
requires the fewest steps.

Now, I am not against complexity in nature.  The life cycle for malaria has 
included a complex number of "hosts" to complete (OOC, is malaria specifically 
a human parasite, or are other critters affected by the "end product").  Also, 
there are many other life cycles that have similar complexities.  So, I won't 
deny that there can be some incredibly complex, and plausible, evolutionary 
lineages.


Rob Meyerson

***
Evil triumphs where good men do nothing.