Re: Greg Paul is right (again); or "Archie's not a birdy"

[Tim Williams <tijawi@gmail.com>]

Scott Hartman <skeletaldrawing@gmail.com> wrote:

> Birds are a living group of animals (that's sure what Linneaus meant
> when he named them) and their most recent common ancestor (and
> associated descendants).  Once we start tossing in taxa further from
> the crown the word becomes more and more misleading.  Birds are known
> to have only one working ovary as their primitive condition...is this
> true of Archaeopteryx? Velociraptor?  What about the palatine?  It was
> assumed (and even described from a poorly preserved version) as having
> the "avian condition" in Archaeopteryx, when better data showed it has
> the more primitive tetraradiate palatine.  In fact, outside of
> feathers (which we now know goes far beyond Archaeopteryx) there is
> almost nothing about it that makes it terribly like crown-group birds.


The palatine is a good example.  Another obvious and arguably more
insidious example is the "perching foot" of _Archaeopteryx_.  It was
assumed that _Archaeopteryx_ had a reversed first toe (=hallux)
suitable for perching, because specimens were preserved with the
hallux in a reversed position, which we now know to be an artifact.  A
good look at the first metatarsal of _Archaeopteryx_ revealed that
there was nothing to suggest that this toe could be held in a
retroverted position in life.  However, one of the reasons why the
"perching foot" had so much support for such a long time was because
_Archaeopteryx_ was a bird, and modern birds have a reversed hallux.
Like _Archaeopteryx_'s (alleged) ability to fly, its (alleged)
perching ability was propelled by typological thinking.



> I know that some people worry that this will create some sort of
> unspecified havoc with the public ("Congress had to postpone the debt
> ceiling issue today as they took up HB155GA: 'Is Archaeopteryx a
> Bird', which has widespread bipartisan support").


The Tea Party insists that _Archaeopteryx_ is a fake.  Also,
_Deinonychus_ is a filthy socialist, because it engages in
pack-hunting.


(That's a joke - I think.)


> Anyone asking an astronomer why Pluto isn't a planet in effect asking
> "So why IS something a planet?", which in the hands of a good educator
> is pure gold.


Ceres was considered a planet for around fifty years.  Not as long as
Pluto, but still a long time.  So science has been through this
before.





Cheers

Tim