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Re: Hanson 2006, Mortimer, Baeker response
Mike Taylor wrote:
I'm not sure I can agree with your position. For example, I've got pretty
bored of repeatedly writing "non-neosauropod sauropod" recently; wouldn't
it be nice just to define Eosauropoda as the paraphyletic group (Sauropoda
- Neosauropoda) and then just refer to eosauropods?
Although "non-neosauropod sauropod" is a cumbersome term, it is also
explicit. I can't see any inherent reason why this term is bad.
"Non-neosauropod sauropod" tells the reader *exactly* what you mean, without
having to invent a new term.
As for the paraphyletic group "Eosauropoda"... this would be difficult to
define using species or specimens. You'd have to come up with a definition
like "All descendents of the most recent common ancestor of A and B, but
excluding all descendents of the most recent common encestor of B and C,
where C is more derived than A." We have enough trouble defining
MONOphyletic groups - defining PARAphyletic groups sounds like buying
> For example, I don't want to back to the bad old days when Theropoda was
paraphyletic, and > birds (Aves) were excluded because they were considered
too "different" to be put in with > the theropods.
That example is misleading, because the confusion arises from two differing
candidate meanings (one monophyletic, the other not) of the same existing
name. I agree with you that it's always bad to have multiple meanings for
a name, but that is orthogonal to whether all names should refer to clades.
I don't think this example is misleading, because a lot of people do
complain about the term "non-avian theropod". But if we are going to define
groups by shared common ancestry (as phylogenetic taxonomy aims to do) then
using paraphyletic groups is counterproductive.
I hate to disappoint you, but you are allowed to use osteological features
and molecular sequences only :-)
Aw shucks. No 'soft anatomy' analyses, huh? :-)
Yes! See Recommendation 11F on page 50:
Recommendation 11F. Clade names created by adding
certain prefixes or suffixes to another clade name
(the base name) should be defined in a manner
consistent with the hierarchical relationships implied
by the prefix or suffix and the phylogenetic
definition of the base name (if established), unless
doing so would be inconsistent with the predominant
current use of a preexisting name.
This would surely only apply to co-ordinated family-level taxa, wouldn't it?
This Recommendation would only affect names ending in -oidea, -idae,
-inae, -ini("superfamily", "family", "subfamily", "tribe", respectively).
This appears to be the current practice anyway, so it shouldn't cause any
problems - so long as these clades are defined with this hierachial
principle in mind. AFAIK, there have never been "standard" suffixes for
"orders", "classes", "phyla", 'kingdoms", etc - for zoological nomenclature,
Note 11F.1. The following prefixes and suffixes imply
greater inclusiveness than the base name: Holo-, Pan-,
-formes, -morpha. The following prefixes imply lesser
inclusiveness than the base name: Eo-, Eu-, Neo-,
Proto-. The following prefixes imply mutual
exclusivity with the base name: Pseudo-, Para-. These
are not intended to be exhaustive lists.
Now this is a great idea. One thing that bewildered me was having the clade
Suchia inside the clade Pseudosuchia - though Pseudosuchia isn't used so
much these days.
I also think it's a great idea to have a clade beginning with Eu- or Neo- to
be inside the corresponding more-inclusive clade, especially given the
situation regarding certain dinosaur clades. For example, Ornithopoda
(node-based) is defined to include _Heterodontosaurus_ but to exclude
_Triceratops_. Thus, if heterodontosaurids are closer to ceratopsians than
to euronithopods, then Ornithopoda is invalid, but Euornithopoda
(stem-based) would continue. This is very silly.