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RE: tiny-armed theropods



  I lost the database I compiled, but at one point, as of *Dromaeosauroides 
bornholmensis*, there were ~147 taxa designated a dinosaur at one point or 
another based solely on a tooth or a collection of teeth (syntype series, with 
lectotypes, etc.).

  Several of these taxa were the basis of further systematic nomenclature, 
either as the root for further "genus" level names, or for containing "family" 
level names, and of these, *Deinodon*, *Trachodon* and *Troodon* were among the 
most prevalently used up to at least 50 years from their time of naming. Some 
of them continue to be used. Expanding the list to *Archosauria* would have 
immensely increased the list, as it would then include crocodylian and 
pterosaurian teeth and such.

  If we were to infer that the tooth or useage thereof is unsuitable for 
taxonomy, and that anything further from that tooth to be unsuitable for 
taxonomy (such as "family"-rank taxa), then we'd lose a lot of so-called 
priority issues. There is a sense that any amount of material, if it's 
"interesting" or distinct in any fashion, can be useful for clarifying 
potential range of diversity in a small area or extend stratigraphy. When this 
is prevalent, one is usually left with what happened in the mid- to late-1990s 
with a plethora of tooth-based "dinosaur" taxa, all of which appear to be 
crurotarsan of one form or another (i.e., like *Revueltosaurus callenderi* ... 
see Irmis et al., 2007: http://socrates.berkeley.edu/~irmisr/trornith.pdf).

  I am, as many others, in general disagreement that taxa are useful when based 
on teeth; while the form is useful, it doesn't _need_ a name, as the name is 
often used in manners that have no respect to the purpose or qualification for 
which the name is given, such as in "conservation" methods where a taxon can be 
granted to "split" a form from conservation status, or increase exposure for 
it, even if the nature of the "species" in this respect is less tenable 
otherwise. Such arbitrary measures do not help scientists trying to figure out 
what species are, or their value or utility. It's more of a "pick and choose" 
process, really.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


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> Date: Fri, 14 Oct 2011 09:55:25 +1100
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: tiny-armed theropods
>
> Matthew Martyniuk <martyniuk@gmail.com> wrote:
>
> > Well, it seems patently absurd to us now. But in the 1960s when some
> > scientists essentially unilaterally decided that the widely used name
> > Deinodontidae was not based on a sufficient enough holotype to be
> > worthy of priority, it may have seemed equally absurd to replace it
> > with newcomer Tyrannosauridae as replacing Troodontidae with
> > Stenonychosauridae would seem to us today, despite being identical
> > situations.
>
>
> Actually, in light of the fact that _Troodon_ is a controversial
> genus, and possibly a nomen dubium (as noted most recently by Zanno et
> al., 2011, for example), the situation you mention is not absurd at
> all. (Although as Mike K. noted, Saurornithoididae would be the
> preferred replacement name). I mooted the possibility of Troodontidae
> being replaced by Saurornithoididae a few years ago:
>
>
> "If _Troodon_ is declared a nomen dubium, then there's no
> objective reason to maintain Troodontidae in preference to Saurornithoididae
> any more than we would use Deinodontidae in preference to Tyrannosauridae."
>
>
> http://dml.cmnh.org/2007Oct/msg00035.html
>
>
> > It's worth remembering that our current "stable" names became that way
> > after unseating previously stable names, sometimes a matter of a
> > decade or two ago (anybody remember Podokesauridae, which was
> > supplanted by Coelophysidae in the early 1990s for no discernible
> > reason)? As far as I know, PhyloCode has no mechanism to preserve this
> > traditional practice of influential researchers arbitrarily replacing
> > stable names with names that they like better. What's a paleontologist
> > in 2100 to do if he suddenly gets the gut feeling that
> > _Therizinosaurus_ is a poor holotype and that the group should
> > obviously be called Nothronychidae?
>
>
> I think you're being a little bit unfair here. Many of these family
> names are not stable, and the practice of replacing them is not
> arbitrary.
>
>
> For the purposes of nomenclatural stability, it's no good having
> families established on crappy genera. Yes, you can do it (such as
> Ceratopsidae, and potentially Troodontidae), but it's not a good
> policy. That's why we no longer use Deinodontidae and Atlantosauridae
> (and haven't for a long time); and why an equally sensible decision
> was made to replace Podokesauridae with Coelophysidae, given the
> uncertainties surrounding the genus _Podokesaurus_. (In addition to
> Tom Holtz's reasons, I would also add that the type specimen of _P.
> holyokensis_ no longer exists, having been destroyed in a fire.)
>
>
>
>
>
>
>
>
> Cheers
>
> Tim