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_Orrorin_ and Formalized Paraphyly



Ken Kinman (kinman@hotmail.com) wrote:

<If Ardipithecus is closer to Pan, then I would simply alter the
traditional classification as follows:
    Pongidae
        1   Pongo
        2   Gorilla
        3A  Ardipithecus
        3B  Pan
        4   {{Hominidae}}
    Hominidae
        1   Orrorin
        2   Australopithecus
       _a_  Homo>

  Or we could do it this way:

--Hominoidea
   |--Pongidae
   |   `--_Pongo_
   `--Hominidae
       |--_Gorilla_
       |--"Paninae"
       |    |-?_Orrorin_
       |    `--_Pan_
       `--Homininae
           |--_Australopithecus_
           `--_Homo_

  ... and avoid paraphyly alltogether. Or whenever possible
without leading to confusion. Why should Hominidae exclude
gorillas and chimpanzees? Is there another Scala Natura scenario
going on here that hasn't been discarded by Leakey and Darwin?

  Sivapithecids have been suggested at the closest relatives to
*Pongo,* but those that do are still advocating a monophyletic
Pongidae with a Ponginae (orang-utans) and Sivapithecinae (well,
you know...); anything closer to man than orangs can be put into
Hominidae or add new names to include Hominidae but not
Pongidae, and keep hominids to Lucy (say) and *Homo,* and their
most recent common ancestor.

  ------------

  Paraphyletic taxa are useful, but not formal designations for
them, which are misleading (see what Mike said). You'd have to
actually do something paratoxonomic to them to avoid people
trying to infer these as realistic taxa and not form-taxa to fit
a concept, rather than a holo- or monophyletic group (based on
strict criteria of inclusion). Thecondontiformes is as bad as
Prolacertiformes, but recent work still suggests that, unlike
the former, the latter is salvageable; comments on it being
dropped (rather than the other) without a phylogeny from which
to state it isn't likely to exist, are statements on their face,
not content.

  We can still say thecodont, but a "Thecodontia" brings up the
crocs and suchs and whatnot critters who had socket-shaped teeth
and must therefore be monophyletic. It ain't real as of early
1980. Prolacertiformes is still used, whether you regard
*Protorosaurus* a member or not [*Prolacerta* does seem to be a
valid monnicker -- the name Prolacertiformes was established on
that name, not to fit a pre-lizard hypothesis, though the genus was].

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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