[Taxacom] Rankless classifications

[Kenneth Kinman]

 Dear All, 
      Below is an example of rankless classification that is
only a hint of what is to come if we continue down this road. These are
just the clades between Tetrapoda and Aves used by NCBI, and it is
relatively simple because they deal almost exclusively with living taxa.
Throw in all the extinct taxa, and it would have far more intermediate
taxa with names most users would not recognize at all. 
      In a traditional classification (with ranks),
Tetrapoda would be divided into just four Classes (Amphibia, Reptila,
Aves, Mammalia. You can go directly from Tetrapoda to Aves, not through
all these intermediate clades (even more between Chordata and Aves).
For most ornithologists (or even amateur bird-watchers) all they need is
the ranked Phylum Chordata and Class Aves (period).  Intermediate taxa
like Avialae (between Coelurosauria and Aves) are just a legalistic
distraction that PhyloCodists love to throw around.  And even worse,
many PhyloCodists want Aves to be a crown group (living birds), while
Archaeopteryx is far outside of Aves (but within Avialae).  By the way,
some strict cladists want to make Amphibia a crown clade (thus excluding
many extinct groups generally classified in Class Amphibia).
   
Sarcopterygii
..Tetrapoda
....Amniota
......Sauropsida
........Sauria
..........Archosauria
............Dinosauria
..............Saurischia
................Theropoda
..................Coelurosauria  
....................Aves                            
                                                
     And how about the cactus example.  Search for Cactales at NCBI and
you get NO RESULTS.  What percentage of classification end-users know
that Cactaceae has been dumped by strict cladists into Carophyllales.
It is quite simple to have a paraphyletic Carophyllales, including a
{{Cactales}} exgroup marker.  Whether you want to call Cactales an
exgroup or autophyletic taxon is just a matter of taste.  What such
terms share is a fundamental recognition that paraphyletic taxa are
often extremely useful.  And just wait until strict cladism hits
arthropods in a big way.  You haven't seen nothing yet.
 
Eukaryota
..Viridiplantae
....Streptophyta
......Streptophytina
........Embryophyta
..........Tracheophyta
............Euphyllophyta
..............Spermatophyta
................Magnoliophyta
..................eudicotyledons
....................core eudicotyledons
......................Caryophyllales
........................Cactaceae           
                                             
              --------Ken Kinman