On Apr 10, 6:51�ソスpm, John Harshman <
jharsh...@pacbell.net> wrote:
> On 4/10/13 3:30 PM, pnyikos wrote:
> > On Apr 10, 5:46 pm, John Harshman<
jharsh...@pacbell.net> �ソスwrote:
> >> On 4/10/13 2:34 PM, alias Ernest Major wrote:
>
> >>> On 10/04/2013 21:56, Richard Norman wrote:
>
> >>>> I would prefer to return to the topic and so I ask John why
> >>>> "traditional systematists" are held in such low regard. Isn't this
> >>>> just a typical arrogance of the molecular people when there is
> >>>> disagreement about lineage? Is there a consensus about turtles or is
> >>>> there really some debate?
>
> >>> I think you'll find that it's not morphological vs molecular, but
> >>> traditional vs cladistic. (I'm all that sure of the low regard either.)
>
> > I think it is molecular vs. morphological that takes into account
> > extinct taxa, like *Eusthenopteron*.
>
> Then you are wrong. I think you're confusing the discussion of turtle
> cladistic relationships (not traditional systematics) with your ideas of
> close relationships to ancestors (traditional).
You misunderstood my intent, and maybe I misunderstood Ernest Major's
intent. I was thinking of the last question Richard Norman asked, as
to wheret the controversy about turtle ancestry is centered.
A number of months ago I read an article by Gauthier in which he
described his latest morphological cladistic analysis, in which
extinct as well as extant species were incuded. Among them was the
enigmatic *Eunotosaurus* as well as the earliest known Chelonian. And
the result was that turtles were classed as anapsids.
> >>> The problem with traditional systematics is baseing classifications on a
> >>> small number of subjectively selected "key" characters, rather than on
> >>> all the evidence.
>
> > Largely true, but subjectivity is in the eye of the beholder.
>
> > For instance, I've said in the past that just the structure of the
> > shoulder girdle in the monotremes vs. marsupials and placentals should
> > outweigh a really hefty number of minor (especially molecular)
> > characters as far as what is the sister group of what.
>
> > The scapula of marsupials and placentals is essentially identical,
> > even to a raised median ridge, while that of monotremes is utterly
> > different.
And harking back to therapsids and even pelycosaurs. There is a
series of fine drawings in Romer's _Vertebrate Paleontology showing
shoulder girdles of *Ophiacodon* (a pelycosaur), *Kannemeyeria* (a
dicynodont), the platypus, and the Virginia opossum. The first three
resemble each other far more than the last two resemble each other,
even when the extra elements of the first three shoulder girdles are
disregarded.
> >�ソスAlso there is at least one extra element in the monotreme
> > shoulder girdle.
Two. The interclavicle and the procoracoid.
> > Harshman's reply was a dismissive "If only it were that simple". �ソスHad
> > I said "all" except "a really hefty" [actually, words to that effect]
> > he would have been on target. �ソスInstead I think it would have been more
> > appropriate for him to say "I'm glad the process we use is not so
> > complicated."
>
> We'll all do better if you stop these retrospective judgments rendered
> to third parties.
You have complete freedom to update your opinion, but you do not avail
yourself of it.
> >> That wasn't quite the "traditional" that Peter was talking about. He was
> >> referring, essentially, to gradism.
>
> > If you are referring to grades as in "subholostean grade" and
> > "holostean grade" you are dead wrong. �ソスThat is the only example of
> > polyphyletic taxon that Romer gave in _Vertebrate Paleontology_, the
> > example of both the bowfin and the gar being in Holostei.
No reply to this from you, so I am still confused by what you mean by
"gradism." For now I will assume you really meant to refer to what I
described next:
> > What I keep referring to is the traditional Linnean classification
> > whereby every organism had its own genus, family, order etc.
> > [including some intermediates like "suborder," "infraorder,"
> > "superfamily" in some cases]. �ソスCladistic classification is great for
> > extant taxa, but the further back in time one goes, the more
> > unsatisfactory it is.
>
> You have confused cladistic classification with unranked classification.
> It's possible to have a cladistic, Linnean classification.
For extant animals, it is. But for extinct species it gets worse and
worse the further back one goes. Organisms are all put at leaves due
to the taboo against depicting them in the position of ancestors. As
a result, stem species could have nothing besides a gigantic clade to
put them in, perhaps one containing the whole of tetrapoda, without
any family or even class to belong to.
In the traditional classification, these are in the paraphyletic class
Amphibia, and whether they are in a family or order all by themselves
is determined by how different they are from the nearest species in
morphology.
> And of course
> you like the traditional classification because it's all about grades.
And all the advantages they provide. And you like the cladistic
because it is willing to pay any price for "objectivity," even at the
cost of being unable to orient oneself without putting untold hours
into studying minutiae.
> > In guides to mushrooms, trees, etc. one has means of identification
> > for non-specialists that classifies things according to spore print
> > and other visible characters. �ソスIf a fossil has the various apomorpies
> > that narrow down its clade missing, at least the Linnean
> > classification gave other ready criteria for identifying it, or at
> > least narrowing it down to the smallest feasible Linnean taxon.
>
> Not really, no.
You have a knack for bland denials. I hope what I say next won't get
the same bland treatment.
Scene: a fossil hunter finds a scapula prartly buried in the ground
and asks an expert anatomist what he makes of it.
"Without removing more of the surrounding matrix, I can't say very
much except that it is a tetrapod, but neither a bird nor a marsupial
nor a placental. Do you know the age of this outcrop?"
"No, it's different from the ones we've identified so far, and the
geologist who could answer that question is already on his way home."
But after the better part of an hour, the fossil hunter uncovers
another bone from the skeleton and calls it to the attention of the
anatomist.
"That settles it!" the anatomist cries. "It's a mammal, perhaps a
monotreme. You've got a very significant find here, perhaps shedding
a lot of light on mammalian relationships. In the few days left to us
before we head for home, we should make every effort to unearth this
entire fossil to take with us. A find like this comes along only a
few times in a lifetime."
Concluded in next reply.
Peter Nyikos