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Mosasaurids (Squamata) from Maastrichtian Phosphates of Morocco

Ben Creisler

A new online paper:

Nathalie Bardet, Alexandra Houssaye, Peggy Vincent, Xabier Pereda
Suberbiola, Mbarek Amaghzaz, Essaid Jourani & Saïd Meslouh (2014)
Mosasaurids (Squamata) from the Maastrichtian Phosphates of Morocco:
Biodiversity, palaeobiogeography and palaeoecology based on tooth
Gondwana Research (advance online publication)
DOI: 10.1016/j.gr.2014.08.014

Mosasaurines dominated mosasaurid faunas in the Maastrichtian
Phosphates of Morocco.
Niche partitioning probably permitted a high diversity of large marine
Multiple species of Prognathodon filled a novel ‘Crush-Cut’ guild of

Mosasaurid squamates are the most numerically abundant, and
taxonomically/ecologically diverse clade of marine amniotes
represented in the Maastrichtian Phosphates of Morocco. With few
exceptions, they are faunally typical of the Southern Mediterranean
Tethys Margin (around palaeolatitude 25°N) and range from the base to
the top of the stage. The Moroccan assemblages include at least 7
genera and 10 species representing a broad spectrum of sizes and
morphologies that illustrate several ecological trends. Noteworthy is
the predominance of Mosasaurinae which are widespread in
contemporaneous outcrops worldwide and constitute 80% and 70% of the
total genus/species number respectively. In contrast, Halisauromorpha
and Russellosaurina (plioplatecarpines) are scarce and tylosaurines
are presently unknown. All of the Moroccan mosasaurids exhibit
characteristic tooth morphologies and can be placed into resource
partitioning morphoguilds indicative of adaptations for piercing,
crushing or cutting. Medium to large predators are found to distribute
along the 'Crush'-'Cut' axis of the morphoguild projection, and a new
'Crush-Cut' guild, previously unrecognised amongst Mesozoic marine
amniotes, accommodates several Prognathodon species. Also of
importance is the lack of mosasaurids along the 'Pierce'-'Crush' axis,
potentially inferring that these ecological niches were occupied by
other marine vertebrates such as selachians and plesiosaurs. In
addition, the relative abundance of mosasaurids throughout the
Maastrichtian series of the Gantour Basin evidences direct ecological
competition or predation phenomena.