Re: Taxon Search

["Jaime A. Headden" <qilongia@yahoo.com>]

Michael Mortimer (mickey_mortimer111@msn.com) wrote:

<However, I have issues with which clades are presented as "active".  It's
basically the clades Sereno uses.  So Tyrannoraptora is active, despite having
an uncertain content (does it include compsognathids? Ornitholestes?
arctometatarsalians?)>

  This may not be of any relevance on the issue of active versus non-active.
For example, if defined or not, the name "Haemothermia" will like be non-active
because the name is simply not being used. This will be based on consensus of
the users, not based on the coder of the matrix, aka, Paul Sereno himself.
These are, because he's started it, initiated with his views on the taxa, but
are certainly prone to change, and the arguments for changing it are tied in
with the discussion in the paper itself, which will be out soon:

  Sereno, P. C., S. McAllister, & and S. L. Brusatte in press.
   _TaxonSearch_: a relational database for suprageneric taxa and
   phylogenetic definitions. _PhyloInformatics_.

  Another issue with the use of Tyrannoraptora and what it should contain is
obvious on the basis of its definition: it will change dependant on the
phylogeny, as will any node-based taxon, and as will any other taxon defined as
a stem or node, especially the taxon Arctometatarsalia, which it can include,
or be a heterodefinitional synonym of.
  
<But Carnosauria is inactive, because he prefers to use Allosauroidea in order
to avoid historical baggage and because non-allosauroid carnosaurians are
disputed.>

  See above. The current incarnation is based on the research of the person who
formulated the system. It is not for Paul's exclusive use, and the upcoming
paper and the submission form will make this clear when it is established.
Given that the site and paper are not "official" yet should also allow us time
to wait to see the philosophy and formulations involved. Meanwhile, enjoy an
excellent paper:

  Sereno, P. C. 2005. The logical basis of phylogenetic taxonomy.
   _Systematic Biology_ 54:595-619.

Abstract:
  "Abstract.?Phylogenetic taxonomy, like modern Linnean taxonomy, was modeled
on a phylogenetic tree rather than a cladogram and, like its predecessor,
perpetuates the use of morphology as a means of recognizing clades. Both
practices have generated confusion in graphical representation, operational
terminology, and definitional rationale in phylogenetic taxonomy, the history
of which is traced. The following points are made: (1) cladograms, rather than
trees or hybrid cladogram-trees, provide the framework for the simplest
graphical depiction of phylogenetic definitions; (2) a complete notational
scheme for phylogenetic definitions is presented that distinguishes symbolic
notation fromshorthand and longhand versions; (3) phylogenetic definitions are
composed of three components (paradigm, specifier, qualifier) arranged in two
fundamental patterns?node and stem; (4) apomorphies do not constitute a
fundamental definitional pattern but rather serve to qualify a stem-based
definition (as do time and geographic range); (5) formulation of phylogenetic
definitions involves three heuristic criteria (stability, simplicity, prior
use); (6) reasoned definitional revision is encouraged and better defined
(textual substitution, first- and second-order revision); and (7) a database,
TaxonSearch, allows rapid recall of taxonomic and definitional information."

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
__________________________________ 
Start your day with Yahoo! - Make it your home page! 
http://www.yahoo.com/r/hs