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Date: Sun, 18 Mar 2001 18:28:50 -0500 (EST)
From: "T. Mike Keesey" <tmk@dinosauricon.com>
To: -Dinosaur Mailing List- <dinosaur@usc.edu>
Cc: -PhyloCode Mailing List- <PhyloCode@ouvaxa.cats.ohiou.edu>
Subject: Re: Megalancosaurus, Longisquama & other oddballs
On Sun, 18 Mar 2001 Dinogeorge@aol.com wrote:
> In a message dated 3/18/01 2:22:27 PM EST, tmk@dinosauricon.com writes:
>
> << It might be a good idea to revise the definition of _Dinosauromorpha_
> (currently Clade(_Dinosauria_ <-- _Pterosauria_)), too, since it would
> also greatly expand if _Pterosauria_ were not included in _Archosauria_.
> Clade(_Iguanodon bernissartensis_ <-- _Pterodactylus antiquus_,
> _Crocodylus niloticus_) might be better. _Pterosauromorpha_ (currently
> Clade(_Pterosauria_ <-- _Dinosauria)) may need revision, too, or it might
> become a synonym of _Prolacertiformes_ (has this ever been defined?)
> (which already might be a synonym of _Protorosauria_). >>
>
> This is a nice dose of the problems inherent in being too inflexible with the
> definitions of higher taxa.
I see it more as a problem inherent in basing definitions on the
assumption that your phylogeny is the correct one, and not heeding
alternative hypotheses.
Definitely a wide sample of phylogenies should be considered in the making
of the companion volume to PhyloCode. Firm definitions are supposed to be
a main benefit of PhyloCode -- the clades exist free of our arbitrary
notions of membership. But it is true that in order to make the system as
backwards-compatible as possible, great care should be taken in
formulating definitions. PhyloCode has many recommendations for this.
While I'm at it, can anyone think of any objections to these definitions?:
_Prolacertiformes_ == Clade(_Prolacerta_ <-- _Passer_, _Trilophosaurus_, _Rhynchosaurus_)
_Protorosauria_ == Clade(_Protorosaurus_ <-- _Passer_, _Trilophosaurus_, _Rhynchosaurus_)
_Archosauria_ == Clade(_Passer_ + _Crocodylus_)
_Pseudosuchia_ == Clade(_Crocodylus_ <-- _Passer_, _Iguanodon_, _Megalosaurus_)
_Avemetatarsalia_ == Clade(_Passer_ + _Iguanodon_ <-- _Crocodylus_)
_Ornithodira_ == Clade(_Pterodactylus_ + _Passer_) within _Archosauria_
_Pterosauromorpha_ == Clade(_Pterodactylus_ <-- _Iguanodon_)
_Dinosauromorpha_ == Clade(_Iguanodon_ <-- _Pterodactylus_, _Crocodylus_)
_Dinosauriformes_ == Clade(_Marasuchus_ + _Iguanodon_ + _Megalosaurus_)
_Dinosauria_ == Clade(_Iguanodon_ + _Megalosaurus_)
(generic names stand for the type species of those genera; taxa listed in
order of precedence)
Application under various phylogenies:
"the standard":
|--_Rhynchosaurus_
|--_Trilophosaurus_
|--_Prolacertiformes_ (=_Protorosauria_)
| |--_Protorosaurus_
| `--_Prolacerta_
`--+--_Pseudosuchia_
| `--_Crocodylus_
`--_Avemetatarsalia_
`--_Ornithodira_
|--_Pterosauromorpha_
| `--_Pterodactylus_
`--_Dinosauromorpha_
`--_Dinosauriformes
|--_Marasuchus_
`--_Dinosauria_
|--_Iguanodon_
`--+--_Megalosaurus_
`--_Passer_
Dilkes:
|--_Protorosauria_
| `--_Protorosaurus_
`--+--_Rhynchosaurus_
`--+--_Prolacertiformes_
| `--_Prolacerta_
`--_Archosauria_
Peters:
|--_Rhynchosaurus_
`--+--_Prolacertiformes_ (=_Protorosauria_, _Pterosauromorpha_)
| |--_Pterodactylus_
| `--+--_Prolacerta_
| `--_Protorosaurus_
`--_Archosauria_
Feduccia et al. (well, they've never produced a cladogram, but if they
did, it might look like this -- I have no idea what they think of
_Pterosauria_, BTW):
_Archosauria_
|--_Rhynchosaurus_
|--_Trilophosaurus_
|--+--_Prolacertiformes_
| | `--_Prolacerta_
| |--_Protorosauria_
| | `--_Protorosaurus_
| `--_Passer_
`--+--_Pseudosuchia_
| `--_Crocodylus_
`--_Dinosauromorpha_
`--_Dinosauriformes_
|--_Marasuchus_
`--_Dinosauria_
|--_Megalosaurus_
`--_Iguanodon_
Just trying my hand....
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