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Re: Combined answer Archaeopteryx running...




Williams, Tim wrote:

>  However, at a certain point (probably early in the Pygostylia) it
> became advantageous to dedicate the manus and carpus to flight, so both were
> absorbed into the wing.

Then why did pterosaurs retain the manus all the way to the K/T?

> Here's what I meant.  I think we both would agree that, on the whole, birds
> such as _Archaeopteryx_, _Rahonavis_ and the North Korean bird ("Proornis")
> had inferior flight capabilities compared to pygostylians.

I would agree that they are inferior to SOME pygostylians.  But I suspect they
were quite adequate for the use the animals actually put them to.  And some
pygosylians have flight capabilities inferior to archaeopteryx.

> I'm not claiming that _Archaeopteryx_ and its morphologically conservative
> ilk were inferior to pygostylians - any more than lungfish are inferior to
> ray-finned fishes.  Sure, Archie had a very conservative anatomy compared to
> modern birds; but the evidence (as I see it) points to Archie being a
> specialized and versatile hunter in its own right.

This is the point I've been trying to make, with the exception that I don't
believe archie's anatomy was particularly conservative.

>  By contrast, the cumbersome flight
> abilities of _Archaeopteryx_ (compared to pygostylians) precluded these
> birds from forging certain novel niches - e.g. anything that involved aerial
> hovering, marathon flights, or stationary take-offs.

And the lack of a hand precluded the later pygostylians from some grasping
maneuvers.  One life style is not inherently 'better' than the other.

Jim