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Re: "Phylogenetic Definitions and Nomenclature..."



At 01:26 AM 3/23/99 EST, Dinogeorge wrote:
>In a message dated 3/22/99 11:11:45 PM EST, MKIRKALDY@aol.com writes:
>
><< The 3/15/99 issue of JVP also reveals the long-awaited "Phylogenetic
> Definitions and Nomenclature of the Major Taxonomic Categories of
> the Carnivorous Dinosauria (Theropoda)," by Kevin Padian, John R.
> Hutchinson, and Thomas R. Holtz, Jr.   >>

[oh, by the way:  Woo Hoo!!  Finally!!!]

>They were beaten into press by Sereno. Should make things interesting...

Yeah, it will.  However, some of the clade names we use are wholly new, and
some use names already established with clear definitions which Sereno
"redefined".

Throughout, MRCA = most recent common ancestor.
Also, authors and dates refer to the paper of the phylogenetic definition of
term: the actual taxon name can often be much older (viz. Marsh's
Ceratosauria), somewhat older (Paul's Avetheropoda), or just slightly older
(my Arctometatarsalia) than the phylogenetic definition.

So, here's the new taxon (okay, old news to the folks on the list):
Eumaniraptora = all descendants of MRCA of _Deinonychus_ and Neornithes.

Here are some differences between our taxonomies where priority favors our
paper:
Ceratosauria = all taxa closer to _Ceratosaurus_ than to Neornithes.  (Rowe,
1989)
        (Sereno uses _Coelophysis_ rather than _Ceratosaurus_)

Maniraptora = all taxa closer to Neornithes than to _Ornithomimus_
(Gauthier, 1986)
        (Sereno uses the definition "all descedants of the MRCA of
_Oviraptor_ and Neornthes", a clade well deserving of a name, but
unfortunately "Maniraptora" already has an explicit definition)

Arctometatarsalia = all taxa closer to _Ornithomimus_ than to Neornithes
(Holtz, 1996)
        (Sereno uses "Ornithomimosauria" for this definition, but cites the
Holtz 1996 paper in the text)

A case of junior subjective synonymy:
Neoceratosauria = all taxa closer to _Ceratosaurus_ than to _Coelophysis_
(Holtz, 1994)
Ceratosauroidea = all taxa closer to _Carnotaurus_ than to _Coelophysis_
(Sereno, 1997)
        (In most recent phylogenies, these are the same clades)

Here are some differences between our taxonomies where priority seems to
favor Sereno:
Neotetanurae = all descendants of MRCA of _Allosaurus_ and Neornithes
        (We use Avetheropoda for the same definition, a term I like a lot
more in this context.  However, neither Neotetanurae nor Avetheropoda had an
explicit phylogenetic taxonomic definition prior to these papers (except in
abstracts), so Sereno's paper arguably now sets the priority)

Deinonychosauria = all descendants of MRCA of _Troodon_ and _Deinonychus_
        (A really unfortunate choice, in my opinion, given the very
unconstrained position of troodontids: they might be the sister taxon to
ornithomimosaurs, to oviraptorosaurs + therizinosauroids, to
eumaniraptorans, to dromaeosaurids, or to higher birds.  Our definition (all
taxa closer to _Deinonychus_ than to Neornithes) would have much the same
content as Sereno's in his cladogram, but would not greatly inflate the
content as in these other options (in which scenarios at least birds, and
possibly oviraptorosaurs, therizinosauroids, ornithomimosaurs, and
tyrannosaurids might be "deinonychosaurs")

Neotheropoda = all descendants of the MRCA of _Coelophysis_ and Neornithes
        (We used _Ceratosaurus_ for _Coelophysis_, in keeping with Bakker's
original use of the term.  In Bakker's scenario (recently supported by
Rauhut), _Ceratosaurus_ was closer to allosaurs + coelurosaurs than were
"podokesaurs" (coelophysoids), and the ceratosaur + tetanurine clade was
called Neotheropoda.)

Cases where it is really tricky (centering on the validity of _The Complete
Dinosaur_ for priority):
In the Holtz & Brett-Surman taxonomy and systematics chapter of _The
Complete Dinosaur_, Dr. Mike & I use the following definitions for allosaur
groups (also used in the Padian et al. paper):
Carnosauria = all taxa closer to _Allosaurus_ than to Neornithes
Allosauroidea = all descendants of the MRCA of _Allosaurus_ and _Sinraptor_
Allosauridae = all taxa closer to _Allosaurus_ than to _Sinraptor_
Sinraptoridae = all taxa closer to _Sinraptor_ than to _Allosaurus_
If the Holtz & Brett-Surman chapter is upheld, then these definitions have
priority over Sereno's (which has Allosauroidea with the same definition as
Carnosauria above, and different definitions for Allosauridae and
Sinraptoridae).  If it isn't, then Sereno's defs. would seem to have priority.

Cases of no contest:
Both papers agree on the definitions of Theropoda, Tetanurae, Coelurosauria,
Maniraptoriformes, Aves, and Neornithes.  Sereno's Paraves (all taxa closer
to Neornithes than to _Oviraptor_) is not named in our paper.  (I certainly
am using that term more often than before, as my currently studies seem to
be placing troodontids as non-eumaniraptoran paravians).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661