Re: classification systems

["T. Mike Keesey" <tkeese1@gl.umbc.edu>]

On Tue, 29 Sep 1998, PALEO MONT wrote:

> Dear Sir-
>       I am reading about classification of the Dinosauria, and I see many
> different levels and systems.  What I would like to know is what system is
> it that you use most often?  I've seen Linnaen Taxonomic Rank, Phylogenetic
> Systematics, Evolutionary Systematics (gradistics), and so on.  What is
> considered the best?  Or are they all used, just in different studies? 
> Also, Families and Orders are broken down into smaller groups, like
> Parvorder, Nanorder, Gigafamily, Grandfamily, Superfamily, Subfamily,
> Tribe, et cetera.  To what extent are Dinosaur groups labeled?  I was just
> wondering how common all of the subdivisions are utilized.

Cladistic (or phylogenetic) taxonomy is becoming the most popular system. 
It uses no absolute ranks above genus -- every taxon is simpy a clade --
one ancestor and all of its descendants. Relative to another clade it
might be a subclade (if it is contained by the other clade), a superclade
(if it contains the other clade), or nothing (if neither clade contains
the other). The scheme mirrors the (hypothesized) phylogenetic history
exactly. 

For a fairly up-to-date cladogram of Dinosauria, see my web pages:
Grand overview:
 http://umbc.edu/~tkeese1/dinosaur/clades.htm
Clickable image diagram with timeline:
 http://umbc.edu/~tkeese1/dinosaur/phylogen.htm
Detailed version (root):
 http://umbc.edu/~tkeese1/dinosaur/taxa/dinosaur.htm

--T. Mike Keesey                                   <tkeese1@gl.umbc.edu>
DINOSAUR WEB PAGES -- http://www.gl.umbc.edu/~tkeese1/dinosaur/index.htm