Re: Fwd: Adios, "Brachiosaurus" brancai

[Paul P <turtlecroc@yahoo.com>]

Okay, i used "taxonomy" interchangeably with "phylogeny" and 
that wasn't quite legal. But i disagree that you can put 
various sets of names on a tree and have it be okay. Your 
Edmontosaurus example below--which i really like by the way--
only strengthens my original point. Although there may very 
well be three (or even more) legal answers, i.e. taxonomies, 
there is only one best answer.   

While it's true that there is as you say no "genericometer", 
i.e. no good diagnostic frame of reference for evaluating 
species versus genus vs. subgenus, etc., that's one of the 
goals of systematics, to label things so that the taxonomy 
makes sense biologically while also reflecting that one true 
phylogeny. 


--- On Sat, 9/12/09, Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:

> From: Thomas R. Holtz, Jr. <tholtz@umd.edu>
> Subject: Re: Fwd: Adios, "Brachiosaurus" brancai
> To: turtlecroc@yahoo.com, dinosaur@usc.edu
> Date: Saturday, September 12, 2009, 8:04 AM
> 
> Paul P wrote:
> > On 11/09/2009, John Wilkins <john.s.wilkins@gmail.com>
> wrote:
> >
> >> Arguing over genera is like arguing over how
> >> best to put books on a shelf.
> >
> > There are many good ways to put books on a shelf, but
> there
> > is only one true taxonomy.
> 
> [snip]
> 
> No, there isn't. There is one true phylogeny: the "Tree of
> Life"--with
> some mangrove-like properties at the bottom but generally
> stems and
> divergent branches towards the top.
> 
> But taxonomy is the procedure for putting labels on the
> parts of the Tree,
> and here you can have a lot a variations that are all
> equally conformable
> to the shape of the Tree, but nonetheless different from
> each other.
> 
> For instance, let's take the edmontosaurs. Assuming for the
> moment that
> the Campanian taxon is basal to the two late Maastrichtian
> forms, and that
> superlong-billed copei is distinct from long-billed
> annectens. The
> following taxonomies are all consistent with this pattern:
> 
> +--Edmontosaurus regalis
> `--+--Edmontosaurus annectens
>         `--Ed
annectens
>         `--Anatosaurus copei
> 
> +--Edmontosaurus regalis
> `--+--Anatosaurus annectens
>         `--Anatotitan copei
> 
> No one is more "right" than the others. And given that
> there is no real
> genericometer, there is no diagnostic referent to use.
> Indeed, even
> species are nebulous constructs (as discussed at
> considerable length in
> Darwin 1859; that is a major theme in the Origin!).
> 
> So taxonomy shall likely always be a matter of some
> disagreement, even if
> the underlying pattern we are trying to label has an
> independent reality.
> 
> -- 
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu   
> Phone: 301-405-4084
> Office: Centreville 1216
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661
> 
> Faculty Director, Earth, Life & Time Program, College
> Park Scholars
> http://www.geol.umd.edu/~jmerck/eltsite/
> Faculty Director, Science & Global Change Program,
> College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
> 
> Mailing Address:    Thomas R. Holtz, Jr.
> Department of Geology
> Building 237, Room 1117
> University of Maryland
> College Park, MD 20742 USA
> 
>