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SOME CLADISTIC SHORTHAND AND OTHER SUBJECTS



Jonathan R. Wagner wrote (quoting me):
<<>It is basically the way the are defined, but there is a difference.  For
>example, Dinosauria is a node based clade {_Triceratops_ + _Corvus_}, so
some
        I applaud Peter's insistance on avoiding suprageneric (above the
generic level) taxa in taxon definitions. It should be noted, however, that
the definition he cites here does *not* necessarily equal the definition we
have come to know and be uncomfortable with around here,  Dinosauria = { +
_Triceratops_, + Aves }.>>

I think that most people stick to genera (or should) nowadays.  Gauthier has
been the only real offender that makes a mess of things with his definitions.
 For example he defined Maniraptora as 'all animals closer to birds than to
Ornithomimosauria,' which is a pain because 'birds' has no definition and is
not a taxon name (there is no Birdia or Birdae or Birdoidea etc) and I don't
believe Ornithomimosauria was even defined in 1986.  I would very much enjoy
Maniraptora being redefined to be 'all animals closer to _Corvus_ (can you
tell what my favorite bird is?) than to _Ornithomimus_.'


<<I have considered Peter's system, and although I like it, I find it
wanting in several respects:>>

It can of course be modified....

<<2) It does not specifically distinguish between types of anchor
taxa. This is not vital to a shorthand, but promotes clarity of
understanding. Peter's system simply invokes taxa, without specifying the
relationship of that taxon to the group, and then adds a functional symbol.
My system specifies the role of the taxon included in the definition, and
omits the functional symbol per se, as this aspect is covered in the use of
{} to denote common ancestry, and may potentially be confused with other
notations.>>

I'm not sure what you mean by this...  Could you clarify what you mean by
'different types of anchor taxa'?

<<3) While it may be minimally sufficient to use <> symbols (and I
think it's quite clever, really), this does not allow for the clear and
convenient incorporation of multiple exclusive anchor taxa. "( A > B > C )"
is not really very easily deciphered.>>

I think the pointy brackets are ingeneous myself.....  I was however thinking
that the slash symble "/" could be used to denote multiple taxa, like: { A >
B / C };  Said: "all those animals that share a more recent common ancestor
with A than with B or C."  Another example could be an overly wordy
redefinition of Maniraptora: {_Corvus_/_Rhea_/_Archaeopteryx_ >
_Ornithomimus_/_Troodon_/_Tyrannosaurus}; Said: "All those animals that share
a more recent common ancestor with _Corvus_ or _Rhea_ or _Archaeopteryx_ than
with _Ornithomimus_ or _Troodon_ or _Tyrannosaurus_."

<<5) As a result of the above, my system has an advantage in terms of
other forms of clade definition (eg. apomorphy based) which, although
perhaps undesirable, are currently accepted ways of defining clades. I did
not reproduce this portion of the system above, as it is largely irrelevant,
and still in dev.>>

I have no idea how I would write an apomorphy based clade in shorthand (and
even less of an idea of why one would want to...), perhaps something like {+
Apomorphy}?

Anyways, no system is set in stone...  I'd be interested in some comments,
perhaps we will all use the same system eventually.

Peter Buchholz
Tetanurae@aol.com

"Kissing . . . is a goodness," he explained.  "It beats the hell out of card
games."