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Re: Hanson 2006, Mortimer, Baeker response
Tim Williams writes:
> Should you wish to publish anything in a scientific journal, your
> reviewers (presumably sober) may insist on a
> 'no-non-monophyletic-taxa pledge'.
I highly doubt it. I don't think we're living in such a
monophyly-thought-police world quite yet.
> Thirdly, stop making me thirsty. It's not yet noon and I have a
> craving for a stout...
>> Yes. Although _Tendaguria_ and _Agustinia_ are (to my eyes at
>> least) a LOT more way out and freaky than something as relatively
>> pedestrian as _Jobaria_, which seems to be merely a late-surviving
>> but otherwise well-behaved "cetiosaurid". (Ha! Paraphylylicious!
> I would say that morphological distinctiveness, like beauty, often
> lies in the eye of the beholder.
Ye-es. But while we would all agree that there is an element of
subjectivity to beauty, I also think you'd be hard-pressed to find
someone who, for example, wouldn't agree that Keira Knightly and
Rachel Weisz are easier on the eye than Maragret Thatcher. Now think
of _Tendaguria_ as Keira Knightly, _Agustinia_ as Rachel Weisz and
_Jobaria_ as Maragret Thatcher :-)
In other words, a lot of this _is_ objective. But that's just my
> I think this is the problem of monotypic families created to
> emphasize the perceived distinctiveness of a 'weird' taxon. Say for
> example we find a new sauropod that appears closely related to
> _Tendaguria_, but is more basal and shows only one of the 'weird'
> features seen in _Tendaguria_. Say this new sauropod has the stumpy
> neural spine, but not the ginormous transverse processes of
> _Tendaguria_. Is it a "tendaguriid" or not?
Ah, the _Titanosaurus_ problem. That is, not a problem at all.
You'll recall from _last_ week's long, pointless argument (:-) that
_Titanosaurus_ was originally named based on characters that are now
not diagnostic to the level of the taxon then erected. No problem:
the name served us well for 100 years, and has now been deprecated.
Same thing applies to "Tedaguriidae": you can raise the name now,
while it's useful; and if in the future it's not useful, tear it down.
I don't think we all need to worry about posterity so much. ("Why
should I care about posterity? What's posterity ever done for me?" --
Groucho Marx.) If we do work that is helpful for, say, a hundred
years, then that's good enough for me. If instead we end in a
situation where we never do anything unless we are sure that it can
stand for all time, the resulting paralysis doesn't help anyone.
>> It's stronger than that, of course: it's _impossible_ to define a
>> node-based taxon based on a single member.
> Yes, but even these clades may end up containing only a single
> member, if the constituent genera used as specifiers are shown to be
Not really; they'd still be based on multiple individuals. (Unless
you were dumb enough to erect a node-based clade on specifiers that
turned out to be parts of the same specimen :-)
>> There's that claim again. Where is this "rule" stated?
> Nowhere, AFAIK.
Well, then, get over it! :-)/2
> But it is firmly ingrained in tradition that families should not
> include other families. There is a logic behind this: If you are
> using familes, then you are implicitly accepting ranks, and if you
> accept ranks, then it is incongruous to have one family contained
> inside another.
All these things are here for our convenience, not us for theirs.
> As Senter puts it, this family-inside-a-family thing is confusing.
> Besides, I think cladistic-based taxonomy has enough problems being
> accepted in some quarters; having "families" inside other
> "families", and "subfamilies" above "families" would be the last
> straw for some folks.
I agree that it is polite to avoid this kind of thing where possible,
and foresighted to make definitions that avoid it where convenient;
but that's as far as I'm prepared to go. Sometimes when naming clades
you just have to break whatever expectations of hierarchy people may
/o ) \/ Mike Taylor <email@example.com> http://www.miketaylor.org.uk
)_v__/\ "An intellectual is a man who says a simple thing in a difficult
way; an artist is a man who says a difficult thing in a simple
way" -- Charles Bukowski.