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Re: Occam, Start Your Engine...



I've decided to weigh in a little on the microraptor tootsy-feathers bit.  
Truly an impressive fossil, and clearly the feathers are attached to the hind 
feet.  But there is no way that a theropod could get its limbs into the flying 
squirrel position illustrated in the Nature paper.  Rather than classic stable 
gliding , the large control surfaces placed distally are clearly control 
surfaces.  Rather than refer to the specimens' rear "wings," we should be 
referring to its rear rudder.
     I admit that this arrangement is consistent with tree gliding behavior, 
though hardly exclusively so.  Undoubtedly the long leg 'rudders' would have 
reduced the animals top speed when running, but this may have been a worthwhile 
trade off if control of ballistic hunting phases (leaps) was important to its 
food gathering style.
     Being consistent with a hypothesis is not enough, the data needs to 
distinguish between competing hypotheses, and I'm not convinced that this 
specimen does that.  Let me give you an example:  At SVP in Mexico city I made 
the explicit prediction that dromaeosaurs and troodonts should have true flight 
adapted feathers.  3 or 4 years ago, not many people where staking their origin 
of flight hypotheses on that.  Naturally when Microraptor and the others were 
described, I breathed a little easier.  Now it's human nature to think: "I 
predicted this, so it must be good evidee that I'm right!"  But that simply 
isn't so, because wing feathers on non-avian theropods is equally consistent 
with the arboreal hypothesis of bird origins.  All my idea had done is manage 
to escape falsification.  Of course the arboreal hypothesis could not be 
falsified by the absence of hindlimb "wings," but it isn't unambiguously 
supported either.

Occam's bulldozer is on the wrong road this time.

Scott Hartman
University of Wyoming
(307) 742-3799