Re: Coelurosaur Analysis update, with Graciliraptor, Atrociraptor, Sinusonasus,

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Tim Williams" <twilliams_alpha@hotmail.com>
Sent: Thursday, May 20, 2004 5:25 PM

> Mickey Mortimer wrote:
>
> >- Archaeopterygids and scansoriopterygids are deinonychosaurs,
>
> A nit-picking nomenclatural observation: Aves (or Avialae) is defined such
> as to include _Archaeopteryx_.  Therefore, under your phylogeny,
> Deinychosauria would be a clade within the Aves; and _Yandangornis_,
> _Sapeornis_ and _Omnivoropteryx_ would be excluded from the bird clade,
> which is anchored in _Archaeopteryx_ and _Vultur_.

This little blunder is a good argument for the following:
1) The definition of phylogenetic names should follow historical usage.
There's no discussion about this anyway (see Recommendation 11A of the
current draft of the PhyloCode: http://www.ohiou.edu/phylocode/art11.html).
There is, however, quite some discussion on what "historical usage" means.
2) For *Aves*, "historical usage" doesn't conform to a certain (set of)
character(s), at least not for *Aves*. Therefore an apomorphy-based
definition shouldn't be used for that name. Neither does "historical usage"
conform to a certain set of taxa (though it does enough so that a
crown-group definition should not be used for *Aves*). Therefore, *Aves*
shouldn't even be used to label the *Archaeopteryx* node.
3) Instead, "historical usage" of *Aves* in reality conforms to a not quite
conscious concept -- that of "birds", which is what *Aves* inescapably
means. Therefore the phylogenetic definition of *Aves* should try to have,
as far as possible, the same contents as this imagination, in order to a)
prevent frequent misuses of the name, b) raise the acceptance of the
PhyloCode among people who still won't have heard at all of phylogenetic
nomenclature before January 1, 200n.
4) Being not fully conscious, this concept is hard to define. But it _is_
relatively easy to tell what is _not_ a bird. _This_ can very easily be
formulated as a stem-based definition with many external anchors: for
example, *Aves* =

{*Passer domesticus* > *Velociraptor mongoliensis*, *Oviraptor
philoceratops*, *Segnosaurus galbinensis*, *Troodon mongoliensis*,
*Sinornithoides youngi*, *Ornithomimus velox*, *Tyrannosaurus rex*,
*Compsognathus longipes*, *Ornitholestes hermanni*, *Coelurus fragilis*,
*Coelophysis bauri*, *Hypsilophodon foxii*, *Crocodylus niloticus*,
*Sphenosuchus acutus*, *Euparkeria capensis*, *Megalancosaurus preonensis*,
*Sorex araneus*}

Unconsciously, Mickey has used this definition or something very much like
it. To me it seems he excluded *Archaeopteryx* from Avialae _because_
dromies and troodontids are not "birds".

(It looks like he wrote Avialae instead of Aves because the former name is
now more commonly used, which is in turn the case because it almost has a
clear definition while Aves currently requires a "sensu", and because it
originally didn't invoke the "concept" of "bird" -- though this advantage
has been lost; too few people know what "ala" means, so Avialae got to
simply replace Aves among researchers of Mesozoic dinosaurs.)