[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Dubious tyrannosaurs and "Kinman-ian" classifications
Nicholas Gardner wrote:
| | |== i.s. Deinodon
| | |--Albertosaurus
| | `--Gorgosaurus
I'd wipe both _Nanotyrannus_ and _Dinotyrannus_ off the slate. The
available evidence strongly supports the referral of both genera to
_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:
Pete Buchholz wrote:
Linnean Systematics were set up in a non-evolutionary world and should be
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
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
Ahh, if only. John V. Jackson would swoon with ecstacy...
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp