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Latoplatecarpus and Plesioplatecarpus, new mosasaurs from North America



From: Ben Creisler
bh480@scn.org

In new issue of Journal of Vertebrate Paleontology:

Takuya Konishi & Michael W. Caldwell (2011)
Two new plioplatecarpine (Squamata, Mosasauridae) genera from the Upper
Cretaceous of North America, and a global phylogenetic analysis of
plioplatecarpines.
Journal of Vertebrate Paleontology 31(4):754-783
DOI: 10.1080/02724634.2011.579023
http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.579023


A new plioplatecarpine taxon, Latoplatecarpus, gen. nov., is proposed here
to incorporate two species, L. willistoni, sp. nov., and L. nichollsae
(comb. nov.). The new genus is currently restricted in distribution to the
lower middle Campanian of North America. Phylogenetic analysis
incorporating 97 morphological characters and 17 ingroup taxa indicates
that (1) Ectenosaurus clidastoides is the basal-most member within the
Plioplatecarpinae; (2) Platecarpus planifrons is generically distinct from
P. tympaniticus; (3) Latoplatecarpus willistoni, gen. et sp. nov.,
constitutes the basal-most member within the clade that is sister to
Platecarpus tympaniticus; and (4) as many as 17 unequivocal character
changes support the clade comprising the three post-middle Campanian
Plioplatecarpus species. Plesioplatecarpus, gen. nov., is erected to
establish Plesioplatecarpus planifrons (comb. nov.). Further, we propose
that the North American specimens referred to Platecarpus somenensis
pertain to Latoplatecarpus nichollsae, based on the available phylogenetic,
ontogenetic, biostratigraphic, and paleobiogeographic data and
interpretations. Consequently, the current study recognizes 11 species
within seven genera to constitute the Plioplatecarpinae. Of anatomical
note, we suggest that quadrates in most plioplatecarpine taxa including
Latoplatecarpus were tilted anteriorly in life, as a result of the
suspensorial articulation forming along the distomedial portion of the long
suprastapedial process that typifies quadrates in plioplatecarpine
mosasaurs.





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