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Re: New Jeholornis specimen



Return salvo to Tim, 

The shoulder glenoid of dromaeosaurs, troodonts, oviraptorosaurs shares about 
the same degree of lateral orientation as Archaeopteryx, so it does not 
provide evidence of relative grade of flight adaptation. 

As for the expanded finger base seen in all Jehol dromaeosaurs, no other 
predator has evolved it. It is such a clear flight adaptation that all other 
possibilities must be ranked as implausible unless really really good 
evidence shows up indicating otherwise. Since basal dromaeosaurs had much 
greater central finger flattening than Arch, and stiffening too, and longer 
primaries relative to the hand, this is superb evidence of more, advanced 
flight. To argue otherwise is too dismiss powerful evidence on an arbitrary 
basis and is not really scientific. 

There are so many advanced flight features in avepectoran dinosaurs that far 
and away the best explanation is advanced relative to Arch flight, it's way 
beyond mere parsimony. 

GP