Re: Question on Anchiornis huxleyi

[Tim Williams <tijawi@gmail.com>]

Mike Habib <biologyinmotion@gmail.com> wrote:

> Joking aside, I think many aspects of that ecotype are going to be
> reasonable tractable to solve in a broadly accurate way, but probably not
> with great precision.


My assumption (or presumption) is that the aerodynamic potential of
these critters (_Archaeopteryx_, _Anchiornis_, _Microraptor_, etc)
will eventually be elucidated - in no small way due to you "flight
mech folks".  :-)    But even then, the exact ecological or behavioral
 function(s) will be far less clear-cut - especially w.r.t. the good
ol' "ground-up" versus "trees-down" thing.  In other words, we'll be
fairly confident on the "how", but not so much on the "why".


Mark Pauline <markpauline@rocketmail.com> wrote:

> Of course no one is suggesting that Aurornis, Anchiornis, or Xiaotingia are
> ancestral to Avialae or Dromaeosauridae, as all of the recent phylogenies I
> am aware of show these animals evolving after those nodes. You two must just
> mean that they may retain different aspects of that hypothetical ancestor.


Yes, pretty much.  For example,  _Anchiornis_ has symmetrical remiges,
whereas those of _Archaeopteryx_ and _Microraptor_ are asymmetrical.
But which kind (asymmetrical or symmetrical) was present in their most
recent common ancestor?  (This would determines whether the
symmetrical vane of _Anchiornis_ is primitive or a reversal.)  Unlike
Matt, I'm not convinced that multiple gains of asymmetry is less
parsimonious than multiple losses of asymmetry.  At least as far as
basal paravians are concerned.  Modern birds are a whole different
matter....





Cheers

Tim