Re: reason for dropping Owen

[AM Yates <Adam.Yates@bristol.ac.uk>]

On Thu, 6 Sep 2001, T. Mike Keesey wrote:

> Padian and May were the first to provide a phylogenetic definition for
> _Dinosauria_. It did not use any of Owen's original three dinosaurian
> species. I believe the draft PhyloCode includes this as an example of an
> improperly converted taxon, and suggests that it be based on Owen's three
> species instead: Clade(_Hylaeosaurus armatus_ + _Iguanodon anglicus_ +
> _Megalosaurus bucklandii_). (NOTE: The ICZN appointed _I. bernissartensis_
> as the neotype of _Iguanodon_, so that may be a better anchor than the
> dubious _I. anglicus_.)

Hmmm. I'm not overly fond of this "use the original content for anchors"
concept in PT. The concept of what various taxa  should or should not
contain has evolved greatly since those taxa were first proposed. Take
Archosauria for example. When Cope first proposed it he included a
rag-tag bunch of reptiles (I can't remember the exact content off the
top of my head but I'm sure plesiosaurs were in there). So is Gauthier's
crown-group definition an improperly converted definition? If it was
properly converted might Archosauria become a synonym of Diapsida or
Sauria or something like that? I thought one goal of PT was to cause
minimum disruption to existing taxon contents during the conversion.
My dislike of Padian's and May's definition of the dinosauria stems not
from the fact that it doesn't use Owen's original taxa (after all one of
them is a nomen dubium) but because they use birds. Although we all feel
secure that birds evolved from within the Theropoda, a vocal minority of
working palaeontologists do not share this view. Furthermore it is just
better if birds are dinosaurs by discovery not by definition.

my two cents

Adam Yates