new Western Interior dinosaurs: a brief breakdown

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

Greetings,

Just recieved the new New Mexico Museum Western Interior volume discussed for 
the last week or so. Here is, very briefly, a rundown
description of the "new" dinosaurian taxa:

_Saurornitholestes robustus_ Sullivan 2006. Holotype is a nearly complete left 
frontal, larger and more than twice as thick of the
equivalent bone in _S. langstoni_. From the De-na-zin Member, Kirtland Fm., mid 
Late Campanian, NM. Referred specimens are teeth and
pedal ungual. Although compared to _S. langstoni_ and _Velociraptor 
mongoliensis_, no comparison made yet to other dromaeosaurids
(e.g., _Bambiraptor_, _Dromaeosaurus_, _Atrociraptor_, etc.).

_Dracorex hogwartsia_ Bakker, Sullivan, Porter, Larson et Saulsbury. Holotype 
is a nearly complete skull with dorsoventral crushing:
a retrodeformed restoration is provided. Also in holotype are atlas, cervical 
4, and cervical 9. Authors advocate a close
relationship with _Stygimoloch_ and _Pachycephalosaurus_, representing a 
radiaton of long-snouted, spiny-nosed, edentulous
premaxillary, large-sized late Maastrichtian pachys. Authors also advocate that 
it is a young adult but as it is the same size as
the published (and two unpublished) skulls of _Stygimoloch_, it cannot be 
included in that genus. They "readily distinguish"
_Dracorex_ from _Stygimoloch_ by the presence of 4 short spikes in its spike 
cluster, rather than 3 hypetrophied ones (as in the
latter). Authors also suggest that as the "principal character" of 
Marginocephalia ("overhang of the occiput") is non-homologous
between pachycephalosaurs and ceratopsians in their interpretation, that 
Marginocephalia is not a natural group.

_Alaskacephale gangloffi_ Sullivan 2006 is a nearly complete left squamosal 
described last year by Gangloff, Fiorillo & Norton (J.
Paleo. 79:997-1001), from the Prince Creek Fm., late Campanian, Alaska. 
Sullivan illustrates another specimen of _Dracorex_-like
pachycephalosaur currently in private hands that lacks big squamosal spikes. In 
other words, it differs from _Dracorex_ is nearly
the same fashion that _Pachycephalosaurus_ differs from _Stygimoloch_. Hmmmm... 
Altenative hypotheses as to taxonomic and
ontogenetic status do seem to raise themselves here, don't they? Sullivan, and 
Bakker et al., both question the value of cladistic
analyses on pachycephalosaurs at present.

_Agujaceratops_ Lucas, Sullivan et Hunt 2006 is, as noted before, a new genus 
for "_Chasmosaurus" mariscalensis_. One hopes that Tom
Lehman was offered the chance to be in on the naming of his beastie after all 
the hard work he's put in on it.

There's a lot of other things in here: new specimen of _Nodocephalosaurus_; an 
unnamed _Eolambia_-like hadrosauromorph from the
Moreno Hills Fm.; description of the large Mexican specimen of _Kritosaurus_; 
sharks; turtles; crocs; footprints; and more.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796