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Piscivorous dinosaur overabundance (Theropoda: Spinosauridae) in mid-Cretaceous of North Africa

Ben Creisler

A new paper:

Madani Benyoucef, Emilie Läng, Lionel Cavin, Kaddour Mebarki, Mohammed
Adaci & Mustapha Bensalah (2015)
Overabundance of piscivorous dinosaurs (Theropoda: Spinosauridae) in
the mid-Cretaceous of North Africa: The Algerian dilemma.
Cretaceous Research 55: 44-55

The informally called 'Continental intercalaire' is a series of
continental and brackish deposits that outcrops in several regions of
North Africa. The age of the series is not well-constrained, but its
upper part, visible in the 'Kem Kem beds' in Morocco and in Bahariya
in Egypt, is regarded as early Cenomanian in age. Spinosaurid remains
are an important component of this series, but records of this
dinosaur are surprisingly rare in Algerian localities of the
'Continental intercalaire'. Here, we describe a vertebrate assemblage
from two localities, Kénadsa and Menaguir, situated in the Guir basin,
Western Algeria. The assemblage comprises hybodont sharks,
sarcopterygian fishes, ray-finned fishes, turtles, crocodiles and
dinosaurs. Among the latter, only teeth of theropods have been
recovered and 94% belong to Spinosaurus. The assemblage is
taxonomically very similar to the Moroccan and Egyptian assemblages
mentioned above. This study: 1) suggests a likely early Cenomanian age
for the Guir basin deposits containing the assemblage; 2) provides a
new evidence of the homogeneity of the early Cenomanian vertebrate
fauna throughout North Africa; and 3) confirms the overabundance of
theropod dinosaurs, especially spinosaurs, in the assemblage showing a
possible shortcut in the vertebrate food chain. The northern most
locality, Menaguir, shows sedimentological and ichnological evidence
of marine influences indicating that the palaeoenvironment shows
spatial heterogeneities.