Fastovsky and Weishampel Textbook Taxa

["Jonathan R. Wagner" <znc14@ttacs1.ttu.edu>]

        The following is an alphabetical listing of taxa defined in
Fastovsky and Weishampel's _The Evolution and Extinction of Dinosaurs. If
you have not read this book, do so NOW! It is fantastic!
        The taxa are listed below along with their definitions in my
shorthand form. Please refer to my posting from yesterday if you cannot
follow this. 
        When I set out to do this yesterday, I though I remembered them
defining a whole bunch of taxa, but, looking through the book, I could only
find these 11 taxa. Of course, these are the ones *explicitly* defined (as
per Padian and May's comments on priority). There are many implicit
definitions (Eurypoda comes to mind) which are inadequate for our purposes.
        Definitions which appear inadequate, or which contradict previous
work, are marked with an asterisk. If I am missing any of these, please
write to me privately and I will post the additions/corrections to the list.
I could swear they define Hadrosaurinae somewhere... 

Ankylosauria            = {+Ankylosauridae, +Nodosauridae}
*Avetheropoda           = {+"birds", +_Megalosaurus_}
Ceratopsia              = {+Psittacosauridae, +Neoceratopsia}
Dinosauria              = {+Saurischia, +Ornithischia}
Eurornithopoda          = {+Hypsilophodontidae, +Iguanodontia}
Heterodontosauridae     = {+_Heterodontosaurus_, +_Lanasaurus_}
Ornithopoda             = {+Heterdontosauridae, +Euornithopoda}
Pachycephalosauria      = {+Pachycephalosauridae, +_Wannanosaurus_}
*Sauropomorpha          = {+_Thecodont...s_, + "sauropods like Brachiosaurus_"}
Stegosauria             = {+_Huayangosaurus_, +_Stegosaurus_}
*Theropoda              = {+_Tyrannosaurus_, +_Coelophysis_}

        _Thecodontosaurus_ is abbreviated above, quotes from text.

        Now the big question becomes, are these valid? Does this count as
publication in a peer-reviewed work? Are any of these (other than those
marked) actually new? Did the authors intend to define these, or were they
just trying to make the book easier to follow?

        A few quick comments come to mind. These are in no way intended to
suggest that the authors of this book did a bad job. It is an excellent
book, and for all I know they were just using other people's definitions.
These are just some thoughts on how this process could be improved.

1) There are no stem-based taxa. Frankly, I am quite frightened at how
readily traditional names are assigned node-based definitions. A properly
constructed stem-based definition is the best way (IMHO) to capture the
intent of a smaller (order to family level) traditional taxon, and is also
the best way to ensure that the traditional members of that taxon are
included. For example, if we were to define Dromaeosauridae =
{+_Velociraptor_, +_Dromaeosaurus}, and this somehow didn't include
_Deinonychus_, we'd be adding a great deal more confusion than if we just
define Dromaeosauridae = {+_Dromaeosaurus, -_Troodon_, -_Ornithomimus_,
-_Passer_, -_Therizinosaurus_, -_Tyrannosaurus_}. That definition pretty
much ensures that coelurosaurs closely related to dromaey are dromaeosaurs,
and other traditionally non-dromaeosaurian taxa will never be dromaeosaurs.
Cool, huh?
        Another useful aspect of stem-based taxa concerns basal critters.
Using the above definitions, if we were to suppose that _Thecodontosaurus_
were more closely related to "sauropods like _Brachiosaurus_" than
_Anchisaurus_, what do we call _Anchisaurus_? Naturally, it is a "basal
saurischian". However, if we use a stem-based definition of Sauropodomorpha
(as I believe is already in the literature, but I'm not sure...), it is
still a (basal) sauropodomorph.

2) Higher taxa are used as anchor taxa. This is not actually a problem for
node based taxa, but can be for stem based taxa, and is unadvisable. It is
more stable and consistant to use taxa which are not subject to the rules of
phylogenetic taxonomy (e.g. species and genera) to define taxa. No matter
what terminology you use, genera and species will not be lost in the
vagaries of a new system, nor does one have to go looking up their
definition in order to figure out what the higher taxon being defines includes.
        Also, of course, for stem based taxon, there is a possibility that
further evidence may show that one of the anchor taxa is *more* inclusive
than the taxon you thought you were defining. Example:
        Taxon X = {+A, +B}      Taxon Y = {+X, -D}

Given the tree topology (((A, B), C), D), this is fine, X includes {A, B}
and Y includes {A, B, C}. However...
Given the tree topology ((A, C),D), B), X includes {A, B, C, D} and what in
the heckfire does Y include? {A, B} is paraphyletic, {A, B, C, D} is no
longer a stem-based taxon. Basically, your taxon Y is now invalid.

        As an aside, you can see how ineffective using higher taxon
definitions is by looking at the above list. With no definitions of
Saurischia or Ornithischia, how is it possible to apply the definition of
Dinosauria?

3) Using vernacular terms as part of a definition. Even when defined
elsewhere, it seems ill-advised to use informal names in defining taxa. For
example, the many definitions in the literature which use "birds" as an
anchor taxon.

        End of rant...
        Wagner
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      Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409
              "That's DOCTOR evil to you..."  -- Austin Powers