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RE: [dinosaur] New Konzhukovia species (temnospondyl) from Permian of South America + Early Triassic polar coprolites + more papers
Tim Williams wrote-
> Frankly, yes. Subjective it may be, but arbitrary it is not. The
> 'subjective' determination is based on scientific expertise and
> experience. In my view, that trumps the arbitrary rules of the ICZN,
> which only avers that the family that was named first gets priority.
> When defining a clade with the eponymous genus as the specifier, it's
> best to use a genus that is actually valid. I know 'validity' is
> sometimes in the eye of the beholder. But for _Deinodon_, I don't
> know of anyone who thinks it's valid. So I can't see any reason why
> Deinodontoidea should supplant Tyrannosauroidea.
> I understand your Spinosauroidea/Torvosauroidea/Megalosauroidea
> example... yes, Megalosauroidea eventually won out. After all, it has
> priority. Recent studies support _Megalosaurus_ as a valid genus, so
> I've got no problem with clade Megalosauroidea.
But Megalosaurus was often viewed as indeterminate prior to Benson et al.'s
(2008) restudy (e.g. Rauhut, 2000; Allain and Chure, 2002) back when only the
lectotype dentary was referred because it was thought multiple large theropods
were preserved at Stonesfield Slate (Morphotypes A and B, etc.). So if we were
having this discussion then, you'd say no one should resurrect Megalosauroidea
because we already have a good definition for Spinosauroidea. But now you're
fine with it. Don't you note the inconsistency? If we find a supposed nomen
dubium is valid in the future, then do we have to change the clade name? Or
are we in a special time where whatever the consensus is for validity for every
taxon now is seen as binding? Or do you not even care, and figure we'll just
go with the flow of whatever feels right for each situation?
And choosing diagnosability is just as arbitrary as anything else. WHY should
specifiers of clades be diagnostic? What's the downside if they're not? And
before you say it again, no you don't have to include a nomen dubium in a
quantified phylogenetic analysis in order to determine its relationships. You
look where the taxa are that it can't be distinguished from, and that range of
the cladogram is where it goes.
> Of course, we could just have names like Megalosauria, Tyrannosauria,
> Oviraptoriformes, Caenagnathia, Caenagnathiformes, etc (and avoid the
> suffix -oidea), which would bypass ICZN altogether.
And destroy historical continuity, plus disrespect the people who named each
family-level clade. Though of those, only Caenagnathia doesn't already exist.
> Yep, I'm aware there's no consensus regarding the 'standard'
> definition of many clades. Aves is a famous/infamous example. I
> agree that PhyloCode should solve these sorts of problems. But having
> coordinated family-level taxa governed by ICZN rules just adds an
> additional (and unnecessary) layer of complication.
It doesn't complicate, it organizes. It's another layer of rules, but if you
always follow all the rules you'll get a definite answer. And if you don't
like that answer, you can petition. I don't get why you prefer a system where
everyone just sorta goes with what they want, and if a consensus forms great,
but if one doesn't no one's actually wrong. Is is selfishness of wanting to
use the names you like, laziness of not wanting to work through the rules, an
anti-authority grudge of thinking we deserve unlimited power over the system?
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