Re: Hanson 2006, Mortimer, Baeker response

[mike@miketaylor.org.uk (Mike Taylor)]

Tim Williams writes:
>> 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.

"_Iguanodon_, _Megalosaurus_, their most recent common ancestor and
all its descendents" also tells the reader *exactly* what you mean,
but you wouldn't for that reason want to have to get by without the
name Dinosauria.  Naming is always and only a convenience, since if
you're able to define the name then you're equally able to just trout
out that definition in place of the name.  It doesn't follow that,
since it's "only" a convenience, it's not important.

> As for the paraphyletic group "Eosauropoda"... this would be
> difficult to define using species or specimens.

A man goes into the doctor's surgery.  He lifts his arm and says,
"Doctor, it hurts when I do this."  The doctor says, "Don't to that,
then".

If you don't want to define Eosauropoda using species or specimens
(and _I_ certainly don't) then just use the clades that are its
motivation.  Eosauropoda = (Sauropoda - Neosauropoda).  What could be
simpler?

> But if we are going to define groups by shared common ancestry (as
> phylogenetic taxonomy aims to do) then using paraphyletic groups is
> counterproductive.

Why?  I've heard a lot of people parrot this position, but I've yet to
hear one person actually _argue_ for it.  Merely stating it repeatedly
doesn't count.

>>      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.

No?  Senter (2005) reasserts its primacy, based on priority of
synonyms, as the correct name for the stem-based group (Crocs not
birds) under phylogenetic nomenclature.  Senter, Phil.  2005.
Phylogenetic taxonomy and the names of the major archosaurian
(Reptilia) clades PaleoBios 25(3): 1-7.

> 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.

I think it's _polite_, but whatever happened to taxonomic freedom?

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  "It's great that we clicked so meanly into the groove as we
         entered the run-in, just as we did last season.  But the run-in
         starts mid-August" -- Paul Tomkins.