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Eremiasaurus, new mosasaur from Morocco



From: Ben Creisler
bcreisler@gmail.com

Also in the new JVP:



Aaron R. H. Leblanc, Michael W. Caldwell & Nathalie Bardet (2012)
A new mosasaurine from the Maastrichtian (Upper Cretaceous) phosphates
of Morocco and its implications for mosasaurine systematics.
Journal of Vertebrate Paleontology 32(1): 82-104
DOI:10.1080/02724634.2012.624145
http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.624145


A new mosasaur, Eremiasaurus heterodontus, gen. et sp. nov., from the
Maastrichtian phosphates of Morocco is described based on the basis of
two specimens: one consisting of a nearly complete skull, vertebral
column, and isolated appendicular elements, and the other a nearly
complete skull with associated vertebral column. This new mosasaur
exhibits a high degree of heterodonty and a large number of pygal
vertebrae, the latter feature expressed to a greater degree only in
Plotosaurus from the Maastrichtian of California. Analysis of a data
matrix of 135 characters and 32 terminal taxa resulted in three
equally most parsimonious trees, and recovered E. heterodontus as the
sister taxon to Plotosaurini. A second analysis incorporating five
species of the globidensine mosasaur Prognathodon recovered 252 most
parsimonious trees. This second analysis also recovered E.
heterodontus as the closest relative to the Plotosaurini, a position
supported by the presence of an internarial bar keel, exclusion of the
prefrontals from the narial borders, narial embayments in the frontal,
and the presence of a quadrate ala groove. A change in the positions
of several key character-state changes in the second analysis not only
supports the exclusion of E. heterodontus from the globidensine
mosasaurs, but also calls into question the monophyly of the
Globidensini and the suite of quadrate and dental characters used to
diagnose this group.