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Re: Fwd: Adios, "Brachiosaurus" brancai

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.


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
        `--Edmontosaurus copei

+--Edmontosaurus regalis
`--+--Anatosaurus 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
Fax: 301-314-9661

Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
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