Monday, September 22, 2014

[Paleontology • 2014] Rhinorex condrupus • A New saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North Americ


Rhinorex condrupus Gates & Scheetz, 2014
Rhinorex attacked by Deinosuchus, a Cretaceous crocodile
illustration: Julius Csotonyi

Abstract
A new hadrosaurid is described from the Upper Cretaceous Neslen Formation of central Utah. Rhinorex condrupus gen. et sp. nov. is diagnosed on the basis of two unique traits, a hook-shaped projection of the nasal anteroventral process and dorsal projection of the posteroventral process of the premaxilla, and is further differentiated from other hadrosaurid species based on the morphology of the nasal (large nasal boss on the posterodorsal corner of the circumnarial fossa, small protuberences on the anterior process, absence of nasal arch), jugal (vertical postorbital process), postorbital (high degree of flexion present on posterior process), and squamosal (inclined anterolateral processes). This new taxon was discovered in estuarine sediments dated at approximately 75 Ma and just 250 km north of the prolific dinosaur-bearing strata of the Kaiparowits Formation, possibly overlapping in time with Gryposaurus monumentensis. Phylogenetic parsimony and Bayesian analyses associate this new taxon with the Gryposaurus clade, even though the type specimen does not possess the diagnostic nasal hump of the latter genus. Comparisons with phylogenetic analyses from other studies show that a current consensus exists between the general structure of the hadrosaurid evolutionary tree, but on closer examination there is little agreement among species relationships.

Keywords: Hadrosauridae, ornithopod, Cretaceous, Utah, Book Cliffs, Neslen Formation, biogeography, phylogenetics Related arti


Terry A. Gates & Rodney Scheetz. 2014. A New saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North America.
Journal of Systematic Paleontology. doi: 10.1080/14772019.2014.950614



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