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RE: Stegosaur volume of Swiss Journal of Geosciences



Tim Williams wrote-

> > I was countering your statement that Ceratopsidae should
> > have never been named by Marsh because Ceratops was so
> > fragmentary.
>
> I didn't have Ceratopsidae in mind when I made that comment. After all, this 
> was the 19th century, so I think we can give Marsh the benefit of the doubt. 
> I was alluding to families named in more recent times that began as monotypic 
> families - like Mussauridae or Agustiniidae or Aberratiodontidae. The fact 
> that these families were named makes them 'available' - which I don't always 
> think is a good thing. It's like you're rewarding workers who erect new 
> families willy-nilly. Other workers are more restrained, and don't 
> automatically erect new families whenever they discover a particularly 
> distinctive new taxon. _Eoraptor_ and _Eocursor_ and _Mononykus_ could have 
> been granted their own families (because they clearly didn't belong to 
> existing ones), but weren't.

People can make bad decisions, but most families were originally monotypic when 
published.  Ceratosauridae, Noasauridae, Abelisauridae, Megalosauridae, 
Spinosauridae, Carcharodontosauridae, Allosauridae, Compsognathidae, 
Ornithomimidae, Alvarezsauridae, Therizinosauridae, Caenagnathidae, 
Oviraptoridae, Troodontidae, Scansoriopterygidae, Confuciusornithidae, 
Hesperornithidae, etc..  Sometimes it works out, sometimes you get a lot of 
synonyms or useless taxa.  Ironically, Mononykus did get a family-level taxon 
named for it, but only after two of your dreaded monotypic families had been 
named- Parvicursoridae and Alvarezsauridae.  No one seems troubled with using 
Alvarezsauridae, but there have been some pretty sad excuses to keep 
Parvicursorinae sunk under Mononykinae.

> > Instead of ditching Ceratopsidae, why don't we define it in
> > a way that will include Ceratops?  "Ceratops montanus <-
> > Protoceratops andrewsi, Leptoceratops gracilis" or
> > something?
>
> Yes, I'm fine with that. However, that means you have to go through the 
> motions of including _Ceratops montanus_ in a phylogenetic analysis. This 
> seems like a pointless exercise - all this extra effort just to have 
> _Ceratops_ remain as the name-giving taxon.

It's not much effort at all to code a fragmentary taxon in an analysis.  Only 
six characters can be coded for Ceratops in the Albertaceratops analysis, for 
instance.  Or two for Makovicky and Norell (2006).  Again I'm astounded that 
you wouldn't even bother going through such minimal steps to test the 
hypothesis before throwing an established taxon out.

>
 All I'm saying is that Sinraptoridae is a better choice than 
Metriacanthosauridae for this clade. I'm not saying that the best-known 
genus should *always* be the name-giver. All I'm saying is that some 
families were named after very poorly known genera, and I don't think 
priority-based taxonomy is always helpful for family-level clades. And 
priority-based taxonomy is not the gold standard anyway - otherwise we 
would use Dryptosauroidea (Marsh, 1890) in place of Tyrannosauroidea 
(Osborn, 1906).


The point is that you don't have an objective taxonomic system.  You say
 Sinraptoridae is better, but I could say "Yangchuanosauridae" is 
better, and there's no way to tell which of us is right since you threw 
out the rule book.  That's the problem once you start ignoring the 
rules- everyone else can do it too, and you may not like their 
subjective, authority-based decisions.

As for Dryptosauroidea (Deinodontoidea has even more priority, btw), 
Podokesauridae/oidea and all the other examples that are ignored 
nowdays, they annoy me.  I think we should either switch names or 
petition the ICZN instead of letting these technically correct names 
float around unused.  I could easily see the advantages to using 
Coelophysidae, Sinraptoridae, Tyrannosauridae, etc., but I want them to 
go through the formal process.  Regardless, at least in the current 
system under the ICZN these are exceptions and aren't supposed to 
happen.  And sometimes they're corrected, like when Sereno tried to use 
and define Oviraptoroidea, but it was pointed out Caenagnathoidea had 
priority.  In your system, these kinds of priority-flouting cases could 
very well be the norm and lead to anarchy and vanity taxonomy.

> No, I think for the sake of taxonomic stability that we need to maintain 
> well-known genera, even when they are found to have inadequate type species. 
> That's why I think it was a good idea to replace the type species of 
> _Iguanodon_, and to do the same for _Stegosaurus_.
>
> I know you know this; but I'm just mentioning these examples to show that 
> switching the type species and/or type specimen is an integral part of 
> taxonomy. It is not 'subversion'. Not all taxonomy is priority-based. 
> Sometimes entirely subjective decisions are made in order preserve taxonomic 
> stability.

I agree it sometimes works out better, like for Cetiosaurus.  I just don't 
think Stegosaurus should be given a new type species.  We've already 
established that the ICZN does not say Stegosaurus' type species must be 
diagnostic for Stegosaurus, Stegosauridae or (especially) Stegosauria to be 
valid.  And that armatus is nested deep enough within Stegosauridae to not 
affect the Phylocode's definitions for that clade or Stegosaurinae (not that 
the ICZN has any particular reason to care how an inactive code is affected).  
You want eponymous clades to be based on genera with diagnostic species, and 
definitions to be based on complete and diagnostic species, but what you want 
doesn't correspond to the rules that are currently dictated by the body being 
petitioned.  We can argue all day over which system we should have, but based 
on which system we DO have, the choice for Stegosaurus armatus is clear.

Mickey Mortimer