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Augustynolophus, new hadrosaur genus (for Saurolophus morrisi) from California



Ben Creisler
bcreisler@gmail.com

A new online paper:

Albert Prieto-Márquez, Jonathan R. Wagner, Phil R. Bell and Luis M.
Chiappe (2014)
The late-surviving ‘duck-billed’ dinosaur Augustynolophus from the
upper Maastrichtian of western North America and crest evolution in
Saurolophini.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S0016756814000284
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=9298467&fulltextType=RA&fileId=S0016756814000284




We amend the taxonomy and provide new anatomical information on the
hadrosaurid dinosaur Saurolophus morrisi (upper Maastrichtian Moreno
Formation, central California, USA) derived from full preparation of
the referred skull roof. The cranial morphology of this species is
distinct enough to justify the new combination Augustynolophus morrisi
gen. nov. The morphology of the nasals and surrounding cranial bones
indicates that A. morrisi sported a solid nasal crest ending in an
elongate triangular plate that extended above the skull roof.
Autapomorphies include a crescentic base of the frontal caudodorsal
process and extension of the process caudal to the frontal ‘dome’;
distal end of nasal crest with knob-like process inflected rostrally;
circumnarial depression lightly incised and weakly emarginated,
adjacent to caudolateral margin of nasal and occupying two-thirds the
width of lateral surface of distal region of crest; and caudal surface
of distal nasal crest subrectangular. We formally establish the new
tribe Saurolophini consisting of Prosaurolophus, Augustynolophus and
Saurolophus. Saurolophin synapomorphies include a premaxilla with
broad arcuate contour of rostrolateral region of thin everted oral
margin and flat and steeply inclined occlusal surface of dentary
dental battery, among other characters. Saurolophin crests evolved
towards increasing caudodorsal length, along with caudal extension of
the circumnarial fossa and involvement into the crest of adjacent
facial elements. Augustynolophus is the second described genus of
North American late Maastrichtian hadrosaurids. Its recognition
implies a greater diversity among late Maastrichtian dinosaur faunas
than previously recognized and is congruent with hypotheses of
endemism and/or provinciality during Late Cretaceous time.