Re: Serenogram

["Jonathan R. Wagner" <znc14@TTACS.TTU.EDU>]

T. Mike Keesey" wrote:
>I just got a look at the non-coelurosaur theropod definitions from
>Sereno's taxonomy paper. Didn't get to see the whole paper, so maybe some
>of this is explained elsewhere, but I have questions, anyway:
        One word of warning: not only does Dr. Sereno apparently ignore
priority (at least from what I've heard of this paper... library doesn't get
Abhandlungen...), but he apparently has no qualms about redefining his own taxa.

>Neotheropoda: Shouldn't this have _Ceratosaurus_, not _Coelophysis_, as an
>anchor? Didn't the original usage (by Bakker) exclude _Coelophysis_?
        Hardly matters, IMHO, since Bakker did not associate his taxon with
a particular common ancestor (De Quiroz and Gauthier criterion for
priority), nor is it explicitly phylogenetic (Padian and May criterion), nor
is is specifically associated with a properly formulated node- or stem-based
definition (rumored to be a new criterion, and a very good one I might add).

>Ceratosauria: Why on Earth did he anchor this with _Coelophysis_????
        More importantly, why did he ignore an already in place and
unquestionably available definition? The world wonders...

>Hmmm... applying his definition of Spinosauridae to the cladogram on my
>site, birds are spinosaurids....
        That's ok, applying Horner 1990's phylogeny to his definition means
that _Hadrosaurus_ is not a hadrosauroid, and he has allowed for the
possibility that _Hadrosaurus_ might be neither a hadrosaurid nor a
hadrosaurine. There is also the possibility that _Lambeosaurus_ may not be a
lambeosaurine.
        Ornithosuchia... Perhaps Dr. Holtz is getting a mild kick out of
this? :)

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Thomas R. Holtz, Jr. wrote:

>Tetanurae is unambiguously defined as all taxa closer to Aves than to
>Ceratosauria (Gauthier, 1986).
        Doesn't Gauthier use "modern birds" in the definition, which would
mean (for those abandoning his definition of Aves) Neornithes? I'm getting a
headache already...

>>Neotetanurae: Does this have precedence or does Avetheropoda?
>Damn good question...  By publication date of *name*, Avetheropoda is older
>by years.  By publication date of usage in a fully cladistic context,
>Avetheropoda is older by weeks.
        It was my understanding that, in the publication you refer to
(Sereno et al. 1994), "Neotetanurae" was simply a node labelled on a
cladogram, and therefore does not satisfy any of the above listed criteria.
Well, I suppose you could make a case for it satisfying the DeQ and G
criterion, but this is extremely weak (for one thing, how would you tell it
was not stem-based, given the practice at the time?).

>By publication date of explicit definition,
>though, Sereno beat out the as-yet-still-in-press Padian et al. paper
>mentioned above.
        Wait, I thought Holtz 1994 was fairly explicit...

>It actually has been defined such in a couple of Holtz abstracts and in a
>peer-reviewed chapter of a book: Holtz & Brett-Surman's Taxonomy &
>Systematics chapter of _The Complete Dinosaur_.
        Which, of course, brings up three questions:
        1) Does intent to define matter? It was not my impression that that
particular chapter specifically intended to define an old or a new taxon.
Does this matter?
        2) Do abstracts count? How about if your just defining an older taxon?
        3) Do textbooks and popular books count? Obviously, this has bearing
on the Fastovsky & Weishampel definitions.
        Although I doubt that there is a clear answer, these questions are
very important to me personally as I attempt to track down who's definition
of the Hadrosauridae has priority. Latest I can figure is:

the Weishampel et al. (1992 _Telmatosaurus_ article) is not explicitly
phylogenetic, but is based on content (contra Kirkland 1998, on _Eolambia_);

F&W 1996 should NOT count, because it's in a darned freshman textbook;

Forster (et al.? I forget now...) 1997 is an SVP abstract, but is only
supplying a definition for a taxon already named... of course, that
definition refers to suprageneric anchor taxa which were not (at the time)
defined phylogenetically, makeing the application of that definition
extremely difficult;

and then there is Sereno's new definition, which as I understand has some
rather unfortunate anchor taxa.

        At this time, it appear to me that Forster et al. 1997 has priority,
with Sereno's anchors for Lambeosaurinae and Hadrosaurinae substituted, the
definition becomes == { _Saurolophus_ + _Parasaurolophus_ }.
        And may Hennig have mercy on our clades.

George Olshevsky wrote:
>See why priority of publication of name makes most sense?
        Except that then how do you determine which definition has priority?
        This is, by the way, a central part of the DeQ&G rules of priority:
of multiple taxa describing the same common ancestor (AAOID), the first
named has priority. The problem is determining which ancestor a taxon refers
to. This would, of course, be easier if someone had realized how obnoxious
this was going to be and headed it off at the pass a while back with clear
suggestions of how priority should work (e.g. criteria), especially for taxa
already named. Trusting the "community" to find its own way seems to have
turned up some unexpected difficulties. Hopefully, once definitions of
traditional taxa are firmly established, these will resolve themselves
("Earth, Chamberlain, 1939").
        Unfortunately, this process will be impeded if egos are allowed to
become involved. This is especially true if individuals widely respected
beyond the study of dinosaurs choose to be uncooperative. Fortunately, it
appears that some of the bigger names in dinosaur systematics are eschewing
an adversarial approach to the conversion to phylogenetic taxonomy and
working together to try and find a middle ground. Hopefully, other workers
bigger and smaller will come around to this more scientifically appropriate
attitude. 

        Wagner
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     Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
 "Only those whose life is short can truly believe that love is forever"-Lorien