[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

[no subject]

Per Mr. Cowen
"Meanwhile, we should go with as uniformitarian
an interpretation as possible: and that says that
Archaeopteryx was NOT four-winged."

Why is that more uniformitarian, if there are
primitive bird-ancestors with 4 wings, then the 4
winged condition would be the standard no?

Mr. Longrich states:
"I found that the feather structure and
arrangement indicated that they were used as
lift-generating winglets, and calculated that
these structures could have significantly
decreased both the stall speed and turning radius
of the bird"

It seems that their being wings stands or falls
upon that statement alone.

Mr. Cowen:
"Those feathers on the hind limbs could have been
for [...] aerodynamic turning in an agile 
runner and hunter"
Wouldn't they not have adaptations for decreasing
stall speed though?  
Is there anything that could distinguish between
feathers for turning while running, and feathers
for turning while gliding/falling flight?

Mr. Marjanovic:
"Bats and pterosaurs don't have such a thing at 
all. A flexible furcula 
clearly helps, but I can't see why it should be 

I think that the arguement being made here is
that its parsimony in the phylogentics of the
evolution of birds requires that such a structre
shoudl be involved in the evolution of bird
flight, rather than that such a structure is
required for flight at all.  Indeed, if its not
present in bats and ptersosaurs and other flying
creatures, doesn't that argue for it being a
specific characteristic and related to flight
that pops up in the bird line? Rather than that
birds developed flight, and then later developed
this and other features?

Mr. Rey
thought the Dial WAIR model was more widely
accepted and I definitively accept that model
much more than any of the others."

But the WAIR model is built upon two feathered
forelimgs, giving the organism a 'hold' to the
slopping/vertical running surfaces. 
Is there are variation of WAIR that invovles the
leg feathers/leg wing?  If WAIR is the activity
that most leads to flight in the evolution of
birds, it requires that the legs be powerfully
developed and devoted to running no? Any
variations away from that, while still in the
"WAIR Stage" would be deleterious to the organism
no, it would interfere with WAIR no? Perhaps, of
course, hindlimbs with flight feathers evolved
after the "WAIR stage" of course.
Plus, you should probably hope that Mr. Longrich
is wrong no? YOu'll have to redo all those
fascinating paintings, adding wing-legs!

And then there was the case of the 4-legged

Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around