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two new papers



Howdy all,

A few new papers I picked up at SVP (exclusive of the Early-to-Mid K volume):

Taquet, P. & D.A. Russell.  1998.  New data on spinosaurid dinosaurs from
the Early Cretaceous of the Sahara.  C.R. Acad. Sci. Paris, Sciences de la
terre et des planetes 327: 347-353.

New specimens of spinosaurids from North Africa: a snout referred to
_Spinosaurus maroccanus_, indicating it was VERY long snouted, and has a
substantial secondary palate (and thus very posteriorly placed choanae
(internal nares)); and a fragement of a shorter snouted form from Gadoufaoua
(Niger) they name _Cristatusaurus lapparenti_.  They also suggest that
_Pelecanimimus_ may be an ornithomimid-mimic, and closer to spinosaurids.
(I am not exactly overwhelmed for the data for this last hypothesis, given
the weight of evidence of shared derived characters between _Pel._ and
Ornithomimidae, and with _Pel._, Ornithomimidae, and Troodontidae).

(Also, the new spinosaurid from Gadoufaoua shown in Sereno et al.'s talk at
SVP is almost certainly the same taxon as the snout referred to _S.
maroccanus_ by Taquet & Russell, but Sereno's taxon is much more complete,
and demonstrates some significant differences from _Spinosaurus_.  As I've
said before, stay tuned for more spinosaurid information).

Also:
Makovicky, P.J. & H.-D. Sues. 1998.  Anatomy and phylogenetic relationships
of the theropod dinosaur _Microvenator celer_ from the Lower Cretaceous of
Montana.  American Museum Novitates 3240: 1-27.  (August 27, 1998 date:
should be coming to the libraries soon, if not already there).

Excellent redescription of _Microvenator_, including some never-before
published drawings of the specimen from Barnum Brown's day (which so the
limb bones before extensive restoration).  It is an oviraptorosaur, its
dentary (yeah, they have what they think is the dentary) is edentulous (and
reminds me a whole heckuvalot of that of _Caudipteryx_...), and lots of
other information.  Peter & Hans provide a new (and quite good, in my
opinion) phylogenetic analysis of the Coelurosauria, with _Allosaurus_,
_Coelophysis_, and _Herrerasaurus_ as progressively distant outgroups.  The
results (they don't use names for any clades above the operational taxonomic
units, but I'll stick them on for reference):

Tyrannosauridae
Maniraptoriformes
  Ornithomimosauria
  Maniraptora
    _Ornitholestes_
    unnamed
      _Coelurus_
      unnamed
        Eumaniraptora
          Deinonychosauria
            Troodontidae
            Dromaeosauridae
          Avialae
        unnamed
          Therizinosauroidea
          Oviraptorosauria
            Oviraptoridae
            _Microvenator_
            Caenagnathidae

I may disagree with a few points here and there, and would add several
characters to the matrix they didn't include, but overall it is a very good
(and useful) (and explicit) analysis.  Peter and Hans recognize that there
is polymorphism WITHIN some of these taxa for some characters, and that such
polymorphism should be incorporated in future studies.

Oh, and be warned: _Coelurus_ is going to be a very important taxon in
future phylogenetic studies, in part due to a new specimen, and in part
because of the implication of this new find on the (mis-) assignment of
previous specimens to _Ornitholestes_.  (Because we are not supposed to
reveal the technical content of presentation of platform talks and posters
at SVP beyond that in the abstract volume without prior express permission
of the authors, I will wait for Miles, Carpenter, or Cloward to give such
before saying more).

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