Dubious tyrannosaurs and "Kinman-ian" classifications

["Tim Williams" <twilliams_alpha@hotmail.com>]

Nicholas Gardner wrote:


> |                    |--Albertosaurinae
> |                    |  |== i.s. Deinodon
> |                    |  |--Albertosaurus
> |                    |  `--Gorgosaurus
[snip]
> |                             `--+?-Nanotyrannus
> |                                `--Tyrannosaurus


I'd wipe both _Nanotyrannus_ and _Dinotyrannus_ off the slate.  The 
available evidence strongly supports the referral of both genera to 
_Tyrannosaurus_.

_Deinodon_ is known only from teeth, so don't lose sleep over its 
assignment: Tyrannosauridae incertae sedis.

_Labocania_ is scrap.  There was a comment on this list regarding this taxon 
by John... err, Josh Smith:

http://www.cmnh.org/fun/dinosaur-archive/1999Aug/msg00404.html


Pete Buchholz wrote:

> Linnean Systematics were set up in a non-evolutionary world and should be 
> abandoned post-haste!!

If not sooner...

One of the reasons I take exception to the "Kinman-ian" System is that it 
retains the unwanted baggage of the traditional Linnaean system.  Any system 
of classification should try and reflect current views on the evolutionary 
process.  I am especially bewildered by the retention of any vestige of the 
Thecodontia as Thecodontiformes.

At one level, "Thecodontiformes" is an oxymoron - the various lineages and 
oddball taxa that were put into the Thecodontia show almost *nothing* in 
common.  This is the very reason why the term "Thecodontia" was discarded in 
the first place (oh, nearly twenty years ago now).

The group Thecodontia was ostensibly united on the basis of certain 
primitive archosaurian/archosauriform traits (like an imperforate 
acetabulum).  Sure, the interrelationships of proteroschians, 
proterochampsids, erythrosuchids, aetosaurs, phytosaurs, rauisuchids, 
poposaurids, sphenosuchians (basal crocopdylomorphs), lagosuchians, 
_Longisquama_, _Sharovipteryx_, _Scleromochlus_, and _Euparkeria_ (to name a 
few) are a little bewildering.  But I think it's worth the time to examine 
the issues that are obstructing a "neat-and-tidy" classification, and nail 
your colors to the mast.  I think retention of Thecodontia (or any of its 
incarnations) are doing paleontology a disservice by merely funneling all 
these disparate groups into "Thecodontiformes" simply for the sake of 
convenience.

At a more fundamental level, Thecodontia/Thecodontiformes is dangerously 
misleading.  It deludes certain people into believing that the Thecodontia 
is a natural grouping, and therefore a reflection of the evolutionary 
process.  It is not.  But, by using such lazy terminology, certain folks can 
get away with sloppy statements like "birds evolved from thecodonts".  As I 
said in a previous post/rant, Thecodontia is a taxonomic fig-leaf: it 
reveals absolutely nothing except the author's own ignorance.


Finally, David Marjanovic wrote:

> Oho! Someone's putting old Archie closer to Dromaeosauridae than to birds, 
> and >nobody protests? :-)

Well, this taxpayer prefers to regard Archie as the sister taxon to the 
clade that includes all other birds.  I also stick to the increasingly passe 
view that dromaeosaurids did *not* evolve from flying ancestors.

> Are people now generally accepting Paul 1988 and :-> :-> Marjanovic 2000 
> who >said that Archie doesn't share more with Pygostylia than with 
> dromaeosaurids?

Ahh, if only.  John V. Jackson would swoon with ecstacy...

:-)




Tim

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