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Gryposaurus latidens (Ornithopoda: Hadrosauridae) osteology

From: Ben Creisler

A new online paper:

Albert Prieto-Márquez (2012)
The skull and appendicular skeleton of Gryposaurus latidens, a
saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the early
Campanian (Cretaceous) of Montana, USA.
Canadian Journal of Earth Sciences (advance online publication)
doi: 10.1139/e11-069

The osteology of the holotype and referred specimens of the
saurolophine hadrosaurid, Gryposaurus latidens, from the lower Two
Medicine Formation of Montana (USA), is described in detail. With an
estimated early Campanian (Late Cretaceous) age, this dinosaur is one
of the oldest known hadrosaurids. Gryposaurus latidens shows several
autapomorphies, including dentary tooth crowns, with an apicobasal
length/mesiodistal width ratio of 1.7–2.2, a single median carina, and
large marginal denticles in sections of the dental battery; deep and
oval depression on the posteroventral premaxillary surface; and, in
the context of Hadrosauridae, a shallow lacrimal process of the
rostral process of the jugal. Furthermore, G. latidens differs from G.
notabilis and G. monumentensis in having a broadly arcuate
anterolateral oral margin of the premaxilla, a posterior margin of the
narial fenestra that is wider than the dorsoventral depth of the
proximal region of the narial bar, with a nasal crest that rises above
the level of the frontals (in adults) and is located above the
posterior margin of the narial fenestra, and wide and shallow
posteroventral margin of the rostral process of the jugal, among other
characters. This study confirmed a previous hypothesis supporting G.
latidens as the sister taxon to a clade composed of the other species
of Gryposaurus.