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Re: Magnapaulia, "new" lambeosaurine from Baja California, Mexico
It's not as black and white as you say, David.
Unfortunately it is. Trust me, I've spent maybe 20 years grappling with
this kind of issue (and I'm only 29).
I understand that the species concept is not a monolithic thing,
There is no such thing as "the species concept". There are, as I wrote,
at least 147 of them, and they all describe different kinds of entities.
but your grudge against the ICZN seems a little unfair to me. The
binomial system is the only way to keep things concise and not
In fact, the binominal* system _introduces_ several sources of confusion
(and, less cruelly so, of wordiness) that are completely unnecessary. I
don't have time to expound on them now...
* From Latin _nomen_ "name", not from Greek _nomos_ "law" as some people
seem to believe. _Nomen_ is a word without an ending.
I'm sort of having trouble articulating my thoughts here, and please
don't consider me a 'crank' for my skepticism or misunderstandings.
Be assured that I don't. All that shows is that you haven't spent a lot
of time informing yourself about this issue and thinking it through.
I don't think Linnean taxonomy should be dismantled/shoved aside. I
think it should complement cladistics; I am a strong believer in
evolutionary grades, too.
You're confusing several issues here. First: Cladistics has nothing to
do with nomenclature; it's just the method(s) of the science of
phylogenetics. It's how you make a tree. Rank-based taxonomy* is a set
of rules on how to make classifications; classifications aren't trees,
and rank-based taxonomy doesn't even tell you whether you should base
those classifications on trees.
* It can be, and has been, argued how Linnaean its current form really is.
Paraphyletic groups (thecodonts, therapsids, hypsilophodonts,
reptilia...) are still useful and such terms are, to my knowledge,
still used. Would you rather say
"non-dinosaurian/pterosaurian/crocodilian archosaurs" or just
Second issue: rank-based taxonomy is not designed for a "gradist"
philosophy of classification, like the one Ernst Mayr advocated. In such
a philosophy, it would be great to assign transitional forms between two
grades to a sort of intermediate category or maybe to both grades at
once. The codes of rank-based nomenclature forbid all that.
Example: A popular book I once read asked the question of how to
classify *Archaeopteryx*, imagined as the intermediate between
"reptiles" and birds. The answer? "Very simple: as a bridge-animal[*] it
stands between the two groups." No, it plainly doesn't. It's simply not
allowed to be between two classes. You _must_ decide whether you assign
old Archie to Reptilia, to Aves, or to a completely new third class of
its own. No other option is allowed.
Third issue: For some purposes, some paraphyletic groups are useful, and
for others, others are useful. What do you do when they overlap? The
codes of rank-based nomenclature don't allow overlapping taxa. What if
first you need to talk about "reptiles" and then you need to talk about
"egg-laying synapsids" (to use an example Mike Keesey used on this list
maybe 10 years ago)? You can't have both in the same classification!
Under the rank-based codes of nomenclature, the only way out is not to
name them, so none of them is ever in a classification at all.
Fourth issue: There aren't enough ranks for everything. As a result,
paraphyletic taxa can compete for a rank with monophyletic taxa. What if
you want to recognize both Reptilia and Amniota, and want to keep the
traditional class rank for Reptilia, but have already assigned the rank
of superclass to Tetrapoda? You're out of luck, or rather, Amniota is.
Of course, this fourth issue comes up even just among monophyletic taxa
alone. (Suppose you want to recognize Class Mammalia and Subphylum
Vertebrata. Further suppose you want to recognize Amniota, Tetrapoda and
Gnathostomata. Which of the three gets the coveted superclass rank? --
OK, OK, introduce a whole new set of ranks and declare Gnathostomata an
infraphylum. Which of Amniota and Tetrapoda wins the celebrity
deathmatch for superclass rank? Or do you introduce yet another whole
new set of ranks? And what if you suddenly want to recognize
Sarcopterygii or Tetrapodomorpha or Osteichthyes or Teleostomi or
whatever? And I could go on!) That's one reason why I dislike ranks so much.
* Sounds better in the original German.