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Re: Ceratosauria vs. Neotheropoda?



Mike Keesey <keesey@gmail.com> wrote:

> I still think, though, that formal names for grades would
> have to follow some other kind of orthographic practice.

I agree.  I've seen grades put in inverted commas; but that's also too 
ambiguous by itself.  Maybe put quasi- in front of the name (e.g., 
quasi-Iguanodontidae, or shortened to q-Iguanodontidae), for quasi- (Latin 
*quasi*, "as it were").  Or put si in front (Latin *si* "if") (e.g., 
si-Iguanodontidae) to emphasize it's not a "real" group (- clade).  

It's worth mentioning that the practice of erecting names for groups that are 
known (or suspected) to be grades has occurred in other disciplines.

For example, last year a paper came out that described a new 'order' of fossil 
spiders, called the Uraraneida ("tailed spiders").  The order was created for 
two Paleozoic spider genera, _Attercopus_ and _Permarachne_, that primitively 
retain anal flagella.  The thing is, at no point did the paper establish that 
these two genera form their own clade - the authors were quite open about the 
possibility that the two genera might be united by plesiomorphic characters.  
Thus, the authors refer to Ururaneida as a 'plesion', which they erected solely 
because "we wish to draw attention to its distinctiveness".

In more ways than one, Uraraneida (the tailed spiders) sounds like the spider 
equivalent of Sauriurae (= Saururae), the long-tailed birds (i.e., the original 
meaning of Saururae/Sauriurae, not the later corruption of the term for an 
alleged _Archaeopteryx_+Enantiornithes clade).  

However, Sauriurae is no longer accepted as a valid name for the grade of 
primitively long-tailed birds (_Archaeopteryx_, _Jeholornis_, etc).  I think 
this is a good idea, because if we were to discuss Sauriurae as a separate 
group, it may be erroneously *assumed* by some to be an independent radiation 
of birds, rather than a series of steps leading to the short-tailed birds 
(Pygostylia).  This is why I'm skeptical of erecting names for grades.

But the practice of having self-consciously paraphyletic 'orders' or 'familes' 
is tolerated elsewhere in paleontology.  That doesn't make it right, I know.  
But there is a recent precedent (Ururaneida), published in a respected 
scientific journal (PNAS).  I guess it depends on what the reviewers let you 
get away with.

Ref:

Selden, P. A., W. A. Shear & M. D. Sutton. (2008). Fossil evidence for the 
origin of spider spinnerets, and a proposed arachnid order. Proc. Nat. Acad. 
Sci. USA 105: 20781-20785




Cheers

Tim




--- On Mon, 11/23/09, Tim Williams <tijawi@yahoo.com> wrote:

> From: Tim Williams <tijawi@yahoo.com>
> Subject: Re: Ceratosauria vs. Neotheropoda?
> To: tijawi@yahoo.com
> Date: Monday, November 23, 2009, 7:12 PM
> 
> 
> --- On Mon, 11/23/09, T. Michael Keesey <keesey@gmail.com>
> wrote:
> 
> 
> > However, nobody has really formalized such a system
> for
> > grades. If
> > you're serious about it, why not follow in the
> footsteps
> > of
> > phylogenetic nomenclature?
> > 
> > 1) In your papers, wherever you want to use names for
> > grades, define
> > them up front. (Gregory Paul did this in Dinosaurs of
> the
> > Air, for
> > example.) Allow them to overlap.
> > 2) If this is something useful, you'll be able to
> convince
> > more and
> > more people to get on board with it.
> > 3) Once there's enough momentum, start to look into
> > codifying the practice.
> > 
> > I still think, though, that formal names for grades
> would
> > have to follow some other kind of orthographic
> practice. 
> 
> 
> This is a bit of a tangent, but the practice of erecting
> names for groups that are known (or suspected) to be grades
> has occurred in other disciplines.
> 
> For example, last year a paper came out in PNAS that
> described a new 'order' of fossil spiders, called the
> Uraraneida ("tailed spiders").  The order was created
> for two genera, _Attercopus_ and _Permarachne_.  The
> thing is, at no point did the paper establish that these two
> genera form their own clade of basal spiders (arachnids) -
> the authors were quite open about the possibility that the
> two genera might be a grade of basal arachnids.  The
> authors refer to Ururaneida as a 'plesion', which they
> erected solely because "we wish to draw attention to its
> distinctiveness".
> 
> Uraraneida sounds like the spider equivalent of Sauriurae
> (or Saururae), for long-tailed birds (the original meaning,
> not the later corruption of the term for an alleged
> _Archaeopteryx_+Enantiornithes clade).  So the practice
> of 
> 
> 
> 
> 
> 
>       
>