Eotriceratops xerinsularis

[Darryl Jones <dinoguy@sympatico.ca>]

Here is a new one that I haven't seen posted (I just got access to it today).

Xiao-chun Wu, Donald B. Brinkman, David A. Eberth, and Dennis R. Braman
Can. J. Earth Sci./Rev. can. sci. Terre 44(9): 1243-1265 (2007)

Abstract: A skeleton of a new ceratopsid dinosaur, Eotriceratops xerinsularis 
gen. et sp. nov., is described in this
paper. It is the first associated vertebrate skeleton found within the upper 20 
m of the Horseshoe Canyon Formation.
Eotriceratops xerinsularis is a large chasmosaurine that differs from other 
chasmosaurines in a unique set of features
in the premaxilla, nasal horn core, squamosal frill, and epijugal. The most 
striking of those features includes an
extremely tall, non-recessed narial process of the premaxilla; the presence of 
greatly elongate, spindle-shaped
epoccipitals on the squamosal frill; a deep, well-demarcated fossa on the 
anteroventral surface of the squamosal frill;
a sharply conical epijugal with a pronounced proximoposterior process and 
separate fossa-like facets for the jugal and
quadratojugal; and the presence of an obliquely extending vascular trace 
meeting a transverse vascular trace ventrally
on the anterior surface of the nasal horn core. Our phylogenetic analysis 
suggests that E. xerinsularis is nested within
a clade including Triceratops, Diceratops, and Torosaurus, which are all from 
late Maastrichtian deposits. The upper 20
m of the Horseshoe Canyon Formation comprises a coal-rich interval 
(Carbon-Thompson coal zone, unit 5), which previously
has been assigned to upper Maastrichtian magnetochrons 31n and 30r, and the 
Mancicorpus gibbus miospore subzone. The
ceratopsid specimen was collected from between the Carbon and Thompson coal 
seams, and thus, is inferred to (1) occur
near the top of magnetochron 31n and (2) have an age of 67.6-68.0 Ma. Large 
chasmosaurine ceratopsids, such as
Triceratops and Torosaurus, have not previously been described from the 
Horseshoe Canyon Formation or from magnetochron
31n or the M. gibbus miospore subzone. Thus, Eotriceratops is distinctly older 
than any other ceratopsid in the
Triceratops group, and the discovery of E. xerinsularis helps fill a 
biostratigraphic gap between early and late
Maastrichtian chasmosaurines.

I am disappointed that there is no restoration of the skull, just drawings of 
the bones found.

Darryl Jones  <dinoguy@sympatico.ca>

For information on tyrannosaurids and
cool activities and information for kids,
visit my web page at:

http://www3.sympatico.ca/dinoguy/