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Re: AFROTHERIA, CROWS & SPECIES CONCEPTS



David Marjanovic (david.marjanovic@gmx.at) wrote [to the dinosaur mailing
list]:

<Great. Let's take this to the PhyloCode mailing list (which hasn't had
any traffic for months) and argue against any ruling about species in at
least  the first version of the PhyloCode, which is after all about
clades. :-)>

  Well, not definitions of a species, per se, but in defining hominid
genera, Camilo Cela-Conde and Frasisco Ayala (2003) suggest a four genus
rule in Hominidae, dumping a lot of new genera, on the basis of so-called
"adaptative criteria"; these were defined by Mayr (a stauch opponent to
cladist theory and phylogenetic taxonomy); quoting Cela-Conde and Ayala
(pg. 7686): "This evolutionary and ecological concept of the genus leads
to identification of three hominid genera, corresponding to three
distinctive adaptative zones: (i) Australopithecus, encompassing the first
hominids that gradually developed bipedalism; (ii) Paranthropus, the
evolutionary branch (incorporating the robust australopithecines) that
colonized the open spaces of the savanna with specialized feeding on hard
vegetables; and (iii) Homo, the branch that evolved large brains and
retained from Australopithecus gracile features, used stone tools, and
developed a more carnivorous diet." Though Cela-Conde and Ayala review
cladistic definitions of hominids and Hominidae, and concepts therein they
fall on the side of Mayr and regard various paraphyletic, adaptation-based
groups of hominids:

  Hominidae
   Sahelanthropus tchadensis
   Praeanthropinae
     Praeanthropus (including Orrorin, and Australopithecus species
       afarensis and portions of africanus, bahrelghazali, anamensis and
       garhi)
     Ardipithecus ramidus
   Australopithecinae
     Australopithecus (including boisei, robustus, africanus, and
       aethiopicus)
   Homininae
     Homo (including Pithecantrhopus, Kenyanthropus, Protanthropus,
       Sinanthropus, Cyphanthropus, Africanthropus, Telanthropus,
       Atlanthropus, Tchadanthropus ...
I'm-gonna-hurt-my-fingers-anthropus
       ...)

  Cela-Conde, C.J. & Ayala, F.J. 2003. Genera of the human lineage.
_Proceedings of the National Academy of Sciences, Philadelphia_ 100 (13):
7684-7689.

  If this would be applied, any set of given features can be used to
define what is and is not a taxon, and the authors are clear in stating
their collection of names and lumping is based on what they consider to be
"excessive genera" for hominids, as if they should be reasonably smaller,
and are loathe to explain why, or how many other extant -idae taxa have
much more complex species arrangements and referrals (to which Mayr
devoted his early career in South-East Asian birds to document). While the
authors rightfully question the neccessary assignment of such ambiguous
taxa as *Orrorin* and *Sahelanthropus* to Hominidae or to reflect the
origin of bipedalism and the gracile face of moderun human development,
they include them nonetheless, at no odds with including *Orrorin* as a
species of *Praeanthropus* along with rightfully upright, bipedal
"man-apes" such as *A. afarensis* ("Lucy"). Though the paper is opf some
historical interest, this would serve as a caution: checks and balances
are absent, this is a do as you will systematic treatment and does not
question or even cast doubt on a cladistic treatment, just stating the
adoption of Mayr's adaptive treatment in perspective and practice.

  The overcomplication and rather ... unique ... perspectives on all parts
of the field of hominid systematics may be a brush fire waiting to happen
and maybe that would be the best and most ideal candidate to test PT on,
given a specimen-based phylogenetic and cladistic treatment. The authors
above, for instance, discuss the often overlapping or contradicting
anatomy of many African specimens in regards to species identification,
arrangement of populations, diagnosis of "genera" on the basis of single
specimens, even if they are more complete than the hypodigms of several
well-recognized australopithecine taxa (including *A. boisei* =
*Paranthropus*).

  ---

  Thanks to Mickey Mortimer for making this appreciated paper available to
me

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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

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