RE: Limbs and niche partitioning

["Norton, Patrick" <Patrick.Norton@state.me.us>]

> the advent of advanced flight and hopping
> locomotion opened up new niches for small birds)

One niche that opened up was the aquatic environment.  Just a thought   
(wildly speculative), but perhaps some of the prerequisites of flight   
(feathers and a flapping ability) evolved in response to cursorial   
dinosaurs exploiting an aquatic environment.  The higher heat transfer   
rate and higher density of water would likely result in stronger   
selective response to adaptations affecting insulation or propulsion,   
lift and drag, particularly in smaller animals---and without the   
hypertrophy of arms or other elements required for aerial flight. Once   
those characteristics evolved, exapting them for aerial flight would not   
seem to be as big a step as going directly from the ground to the air.  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.

Pat