RE: Peering at review (Triassic dino-birds)

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Tracy Ford wrote:
 
> Lets put it this way, go outside and see how many birds are flying
> around.  Take your time. How many will those fossilize? How many 
> animals will fossilize in a tropical forest? How many animals are living 
> there? When a fossil tropical forest is found in the geological record and

> little or no fossils, are we then to ASSUME that there were no or little 
> animals living there because none or few were found? 

I know the odds are against the preservation of small, tree-dwelling
critters with gracile skeletons.  Nevertheless, some of these critters do
occasionally turn up in the Permo-Triassic fossil record: _Coelurosauravus_,
drepanosaurids*, kuehneosaurids, _Longisquama_, _Sharovipteryx_...
Hypothetical Triassic dino-birds are conspicuous by their absence.  

Sure, these Triassic dino-birds might have existed - I'm not saying they
didn't.  But when this fact is coupled with (a) the absence of
arboreal/scansorial/glissant adaptations in any known basal dinosaur or
basal theropod and (b) the earliest known flying dinosaur (_Archaeopteryx_)
is very primitive by avian standards, then I think we can be forgiven for
avering that the absence of arboreal gliders with dinosaurian affinities
from the Permo-Triassic record might well be real.


Tim

* I know drepanosaurids have also been re-interpreted as aquatic swimmers;
but I think the evidence favors arboreal (chameleon-like?) habits for these
critters.