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Re: Cladistic definitions of Dinosauria, Saurischia, Sauropodomorpha
> Date: Mon, 19 Sep 2005 08:52:21 -0700
> From: "T. Michael Keesey" <email@example.com>
>> Are there "generally accepted" cladistic definitions of Dinosauria,
>> Saurischia and Sauropodomorpha that seem to be winning out?
First up, Mike, thanks for these excepts and citations. Very helpful.
> * Padian and May 1993: "all descendants of the most recent common
> ancestor of birds and _Triceratops_"
> * Sereno 1998: "_Triceratops_, Neornithes, their most recent common
> ancestor and all descendants"
> * Kischlat 2002: [...] "the most recent common ancestor between [i.e.
> "of"] _Megalosaurus_ (a saurischian) and _Hylaeosaurus_ (an
> ornithischian), as well as all its descendants, including the birds"
> * Clarke 2004: "the clade comprised of the most recent common ancestor
> of Owen's (1842) specifiers for his 'Dinosauria' (_Megalosaurus_ and
> _Iguanodon_) and all of its descendants"
Well, I am firmly in the don't-use-birds-as-anchors camp, so that
pushes Padian and May's and Sereno's definitions out the door. That
leaves me with a choice of a non-English language definition --
unappealing -- or Julia Clarke's formulation. The problem with that
is that Clarke in context is clearly not proposing a definition but
Other previously phylogenetically defined taxon names
are repeatedly used throughout the current document.
To briefly summarize the usage of these names:
``Dinosauria'' is used as a node-based name for the
clade comprised of the most recent common ancestor of
Owen's (1842) specifiers for his ``Dinosauria''
(Megalosaurus and Iguanodon) and all of its
descendants; ``Theropoda'' (Gauthier, 1986) refers to
Aves and all saurishian dinosaurs more closely related
to Aves than Sauropodomorpha [...]
It's as though she just forgot the citation.
Also, I need a definition of Saurischia, which should clearly be the
stem (_Megalosaurus_ not _Iguanodon_) if we're using Dinosauria sensu
Clarke. She doesn't mention this clade at all; surely it can't be
that no-one has ever published this definition?
/o ) \/ Mike Taylor <firstname.lastname@example.org> http://www.miketaylor.org.uk
)_v__/\ "You cannot simultaneously have mass adoption and rigor" --