Message 2002-04-0013: Re: eumaniraptoran systematics

Tue, 30 Apr 2002 01:26:10 +0200

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Date: Tue, 30 Apr 2002 01:26:10 +0200
From: David Marjanovic <david.marjanovic@gmx.at>
To: dinosaur@usc.edu, Mailing List - PhyloCode <PhyloCode@ouvaxa.cats.ohiou.edu>
Subject: Re: eumaniraptoran systematics

Sorry for the cross-posting...

> The "Clade(x)" notation is also consistent with mathematical and
computational
> function notation. Perhaps when species are added to PhyloCode, a similar
> "Species(x)" notation could be added, e.g. _rex_ Osborn 1905 =
> Species(CM 9380) (meaning that the species' holotype is CM 9380 -- species
> based on cotypes could use comma-separated lists, etc.).

Interesting idea.

> I agree about the "greater-than" sign (sorry guys!!).

I don't. For me, it points in the right direction. {*Passer domesticus* >
*Deinonychus antirrhopus*} means "to find the clade, begin at *P. d.* and go
all the way down the tree until the point where *D. a.* branches off". The >
is not just an arrowhead (that could be given a shaft), it's also a part of
a line around the clade -- in some cladograms, stem-based taxa are indicated
by writing their names next to a --) part in a tree; a node-stem triplet
then shows up as --)O(-- (not at an angle of 180, of course). The arrow
could, in my opinion, only be used to indicate such a thing if it is made
explicit that it means "to find the clade, begin at the point where *D. a.*
branches off the clade that leads up to *P. d.*", means,  <--| or <--)
instead of <-- .
        However, the usage of > shown above contrasts with the common habit
of putting the "most derived" group at the right end of a cladogram. The
ideal compromise, for me, would be {*Deinonychus antirrhopus* |<-- *Passer
domesticus*} for the clade intended above.
        (I like *Passer domesticus* more than *Vultur gryphus* when "extant
birds" is meant; it's just a lot more archetypical, and [artificially] it
enjoys a worldwide distribution. Actually, I consider *Vultur* a misnomer,
as it is a New World vulture, while the Latin word vultur was for trivial
reasons only applied to certain Old World vultures... but I digress.)
        (Sorry for my long-winded sentences. I'd need to draw what I've
written, and it's quarter past one at night.)

> (It also occurs to me that naming the stems "Troodontia" and
"Dromaeosauria"
> instead of Troodontoidea and Dromaeosauroidea would work, too, especially
given
> the widespread use of the vernacular forms "troodont" and "dromaeosaur"
for
> these groups.)

Good idea. Has the extra advantage of not implying that groups with the same
name roots but different endings must be inside it... OK, that's only an
advantage in times of uncertain phylogenies :-)

> The problem with names based on traits, like "Psalidorhina", is that
either
> 1) They are given node- or stem-based definitions, which rarely if ever
> correspond

respectively can be known to correspond

> precisely to presence of the trait (e.g., _Amniota_, discussed
> recently on the Dinosaur Mailing List), [...]
>
> (Although it is kind of a cool name.)

I agree :-)


  

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