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RE: Kosmoceratops, Utahceratops & Vagaceratops: the paper



The high degree of taxonomic provincialism exhibited by ceratopsians makes me 
wonder what "Torosaurus" utahensis represents. To the best of my knowledge, 
specimens which could be referred to subadults of the northern "Torosaurus" 
(Triceratops) have not been described from Utah/New Mexico/Texas.  If true, 
this suggests the possibility that "Torosaurus" utahensis may represent an 
entirely different taxon...
 
Guy Leahy


> Date: Wed, 22 Sep 2010 11:41:14 -0400
> From: tholtz@umd.edu
> To: dinosaur@usc.edu
> Subject: Kosmoceratops, Utahceratops & Vagaceratops: the paper
> 
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012292
> 
> 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
> 
> Abstract
> 
> Background
> 
> 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.
> Methodology/Principal Findings
> 
> 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.
> Conclusions/Significance
> 
> 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:
> http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2
> Fjournal.pone.0012292.g007&representation=PNG_M
> 
> It's PLoS ONE, so everyone has access.
> 
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu Phone: 301-405-4084
> Office: Centreville 1216 
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661 
> 
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
> 
> Mailing Address: Thomas R. Holtz, Jr.
> Department of Geology
> Building 237, Room 1117
> University of Maryland
> College Park, MD 20742 USA
>