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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.