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Plioplatecarpus peckensis, new mosasaur species from Montana

Ben Creisler

A new online paper:

Robin S. Cuthbertson & Robert B. Holmes (2015)
A new species of Plioplatecarpus (Mosasauridae, Plioplatecarpinae)
from the Bearpaw Formation (Campanian, Upper Cretaceous) of Montana,
Journal of Vertebrate Paleontology (advance online publication)

MOR 1062 is a plioplatecarpine mosasaur that is represented by a
nearly complete skull, complete cervical series, and partial dorsal
vertebral column. The specimen, collected from Upper Cretaceous
(Campanian) deposits of northeast Montana, exhibits a pristine level
of preservation, yielding morphological details not typically
observed. Phylogenetic analysis recovers MOR 1062 within an unresolved
trichotomy with Plioplatecarpus marshi and P. houzeaui. However, based
on the following autapomorphies, a new taxon, Plioplatecarpus
peckensis, sp. nov., is erected to accommodate this suite of features
exhibited by MOR 1062: a narrow, elongate prenarial portion of the
premaxilla that is constricted at midlength; a maxilla with a nearly
straight narial margin in lateral view; a short prefrontal lamina of
maxilla that contributes to a very low profile of the snout
immediately anterior to orbits; a suspensorial ramus of parietal that
does not rotate into horizontal plane distally; nine or 10 pterygoid
teeth; an otosphenoidal crest that covers the exit for cranial nerve
VII in lateral view; jugular and condylar (= hypoglossal) foramina
that exit separately; axial spine with a distinctly notched dorsal
border; hypapophyseal peduncles on postcranial vertebrae 2–7; and
hypapophyses 2–5 bearing paired, anteriorly projecting knobs.