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Re: Defining Ornithischia (was Re:)
David Marjanovic writes:
> > Mr. Peters is using a character-based definition for
> > Paranornithischia. For example, Mr. Peters regards
> > the following characters as important in establishing
> > a relationship between Lotosaurus, Silesaurus and
> > Lesothosaurus:
> > 1. Ventral maxilla is narrow.
> > 2. The orbit marks the halfway point of the skull.
> > 3. The quadrate rises vertically and is concave
> > posteriorly.
> That is not a definition. It is a diagnosis. A definition would
> have to mention at least one organism.
A phylogenetic definition would have to mention at least one organism,
yes; but there are other kinds of definitions, and for most of the
last 249 years, "key character"-based definitions were almost
Don't get me wrong, I think phylogenetic definitions are definitely
the way to go; but to say that any other definition is not a
definition is revisionism.
Anyway, there's nothing to stop me defining Interestingdinosauria as
all members of Dinosauria that massed more than 10,000 kg.
/o ) \/ Mike Taylor <email@example.com> http://www.miketaylor.org.uk
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