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Re: Princeton Field Guide
> And donât get me started with what is going on about all the stuff
being tossed into Mamenchisaurus and Omeisaurus.
Oh yeah. I'd love to see a phylogenetic analyses of the 10 or so
"species" that have ended up, seemingly at random, in these two "genera".
There are a few properly handled dinosaur genera that include a
normal, large number of species such as Psittacosaurus, Apatosaurus
(some species not yet named), Diplodocus (ditto). But dinopaleo has
gotten into the bad habit of usually making almost every species
into its own genus. This is illogical considering that many modern
bird and mammals contain large numbers of species â Varanus (now
formally includes Megalania), Panthera, Felis, Canis, Vulpes,
Cervus, Tragelaphus, Cephalophus, Ovis, Gazella, Macropus,
Balaenoptera, Buteo, Falco, Anas.
*Varanus* is a nightmare with 70 species. The sooner it gets blasted to
tiny bits, the better. (We can't simply use the existing subgenera
because there's no evidence they're monophyletic.) And this goes triply
and quadruply for *Anolis*, the excruciatingly bad joke with 300 species.
*Felis* has been shrinking for decades. *Panthera* contains species that
are really hard to tell apart based on bones alone. *Gazella* and
*Macropus* should be fragmented, and *Anas* is something of a joke,
IIRC; I don't know the others well.
I note you don't mention *Bufo* and *Rana* (they're neither birds nor
mammals, but neither is *Varanus*). Both have been blown to pieces recently.
I see that ceratopsid genera are now actually being defined entirely
on differences in their cranial adornments â thatâs a mind blowing
development â when these are of course specific level in nature.
See, this kind of statement is just wrong. There are no such levels in
nature. A genus is whatever you want it to be.
In an SVP abstract it is stated that ceratopsians were evolving lots
of genera when the degree of variation they are refering to is
actually the minor specific grade. Many in dinopaleo seem to have
forgotten that the most prolific level of evolution is SPECIATION,
not GENUATION, with evolution churning out the minor variants we call
species in far greater numbers than the larger divergences that are
gathered into a genus. Matters have gotten out way of out hand, and
when finishing the book I could not use all the pseudogenera because
people would presume I actually accepted them (as in âeven Greg Paul
agrees that Agujaceratops and Corythosaurus are real genera). Someone
needs to call out the taxonomic madness instead of facilitating it
(the usual names are of course noted).
First, it should be "generation", not "genuation" (_genus_ belongs to
the consonantic declension, not the U declension); second, it doesn't
matter, because no such process exists. There is no genus level of
evolution. There isn't even a species level of evolution. _The_ level of
evolution is the population level. "Macroevolution" is just
microevolution seen from afar. There is no evidence for any processes in
evolution other than mutation, selection and drift.
OK, "species" has at least been defined, even though the 147 different
definitions (as of February 2008) have nothing in common except the word
"species" and lead to a stupendous variety of results (depending on the
species concept, there are from 101 to 249 endemic extant bird species
in Mexico). So, once you have picked a species concept, there is such a
thing as speciation, even though that means different processes count as
speciation for different people. But genera? The only attempt at a genus
concept I've ever seen is "if they can have fertile offspring, they're
in the same species; if they can have sterile offspring, they're in
different species of the same genus; if they can't have offspring,
they're in different genera", but this not only presupposes one of the
Biological Species Concepts, it's laughably impractical, for instance
completely inapplicable to fossils.
Genera don't exist outside our heads! And don't think I'm singling you
out. If that SVP meeting abstract claims to count the genera that
evolved, its authors have fallen into that very same trap.
There are also a number of cases in which what are clearly juveniles
(perhaps with some sexual variation thrown in) are being assigned
their own genus distinct from their adults, this is especially true
of some oviraptors and pachycephalosaurs.
That I'm looking forward to reading about!
It cannot be overemphasized how the nested classification system is
virtually useless for a popular field guide, it providing no graded
structure that the public can latch onto.
For a field guide, why have a classification at all? One that pretends
to be relevant to biology, I mean. I like field guides to presume
complete ignorance on my part, so when I see a yellow flower and want to
look up what it is, I can just look under "yellow" instead of under
Monophyletic clade only classification is a slap at the public
already skeptical about scientists whom they see as elitists who
donât care all that much with communicating with ordinary folks.
So are Linnaean ranks. Do you really believe anyone in "the public"
cares whether Ornithischia is an order or a subclass?
Phylogenetic nomenclature is at least useful for _someone_ (biologists,
In any case the phylogenetic classifications disagree with one
another so much that I threw up my hands
Rank-based classifications disagree with each other even more. That's
because they have two sources of instability: changes in our knowledge
of phylogeny, and mood swings on the part of whoever can be bothered to
publish a classification. "No, I don't think they're subfamilies of the
same family anymore, they're different enough that now I feel they
should be different families in a new subfamily" is a perfectly valid
argument under rank-based nomenclature. Under phylogenetic nomenclature,
it's irrelevant because ranks don't matter.
and cobbled what I could together (an SVP abstract on how difficult
it is to place heterodontosaurs relative to other ornithischians
addresses this problem).
I don't think we should hide our ignorance of phylogeny.