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Kosmoceratops, Utahceratops & Vagaceratops: the paper
Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, et al. (2010) New
Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur
Endemism. PLoS ONE 5(9): e12292. doi:10.1371/journal.pone.0012292
During much of the Late Cretaceous, a shallow, epeiric sea divided North
America into eastern and western landmasses. The western landmass, known as
Laramidia, although diminutive in size, witnessed a major evolutionary
radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the
most common dinosaurs were ceratopsids (large-bodied horned dinosaurs),
currently known only from Laramidia and Asia. Remarkably, previous studies
have postulated the occurrence of latitudinally arrayed dinosaur
"provinces," or "biomes," on Laramidia. Yet this hypothesis has been
challenged on multiple fronts and has remained poorly tested.
Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous
Kaiparowits Formation of Utah that provide the strongest support to date for
the dinosaur provincialism hypothesis. Both pertain to the clade of
ceratopsids known as Chasmosaurinae, dramatically increasing representation
of this group from the southern portion of the Western Interior Basin of
North America. Utahceratops gettyi gen. et sp. nov.-characterized by short,
rounded, laterally projecting supraorbital horncores and an elongate frill
with a deep median embayment-is recovered as the sister taxon to
Pentaceratops sternbergii from the late Campanian of New Mexico.
Kosmoceratops richardsoni gen. et sp. nov.-characterized by elongate,
laterally projecting supraorbital horncores and a short, broad frill adorned
with ten well developed hooks-has the most ornate skull of any known
dinosaur and is closely allied to Chasmosaurus irvinensis from the late
Campanian of Alberta.
Considered in unison, the phylogenetic, stratigraphic, and biogeographic
evidence documents distinct, co-occurring chasmosaurine taxa north and south
on the diminutive landmass of Laramidia. The famous Triceratops and all
other, more nested chasmosaurines are postulated as descendants of forms
previously restricted to the southern portion of Laramidia. Results further
suggest the presence of latitudinally arrayed evolutionary centers of
endemism within chasmosaurine ceratopsids during the late Campanian, the
first documented occurrence of intracontinental endemism within dinosaurs.
Vagaceratops is the former "Chasmosaurus" irvinensis.
A kick-ass (technical term) phylogeny is presented:
It's PLoS ONE, so everyone has access.
Thomas R. Holtz, Jr.
Email: firstname.lastname@example.org Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Faculty Director, Science & Global Change Program, College Park Scholars
Mailing Address: Thomas R. Holtz, Jr.
Department of Geology
Building 237, Room 1117
University of Maryland
College Park, MD 20742 USA