Carcharodontosaurus is a genus of carnivorous carcharodontosaurid
dinosaurs that existed between 100 and 93 million years ago, during the late
Albian to early Cenomanian stages of the mid-Cretaceous Period. It is currently
known to include two species, C.saharicus and C.iguidensis, which were
among the larger theropods, as large as or slightly bigger than Tyrannosaurus
and possibly slightly larger than Giganotosaurus, but not quite as large
as Spinosaurus. The genus Carcharodontosaurus is named
after the shark genus Carcharodon meaning "jagged" or "sharp" and οδοντο
meaning "teeth")), and σαυρος, meaning "lizard".
Description Carcharodontosaurus includes some of the
longest and heaviest known carnivorous dinosaurs, with various scientists
proposing length estimates for the species C. saharicus ranging between 12
and 13.3 m and weight estimates between 6.1 and 15.1 metric tons.
Carcharodontosaurus were carnivores, with enormous jaws and long, serrated
teeth up to eight inches long. A skull length of about 1.6 meters has been
restored for C. saharicus, and the skull of C. iguidensis is reported to have
been about the same size. Currently, the largest known theropod skull belongs to
another huge carcharodontosaurid dinosaur, the closely related
Giganotosaurus. Gregory S. Paul estimates Carcharodontosaurus iguidensis
at 10 m and 4 t. = Brain and inner ear =
In 2001, Hans C. E. Larsson published a description of the inner ear and
endocranium of Carcharodontosaurus saharicus. Starting from the portion of
the brain closest to the tip of the animal's snout is the forebrain, which
is followed by the midbrain. The midbrain is angled downwards at a 45
degree angle and towards the rear of the animal. This is followed by the hind
brain, which is roughly parallel to the forebrain and forms a roughly 40 degree
angle with the midbrain. Overall, the brain of C. saharicus would have been
similar to that of a related dinosaur, Allosaurus fragilis. Larsson found that
the ratio of the cerebrum to the volume of the brain overall in
Carcharodontosaurus was typical for a non-avian reptile. Carcharodontosaurus
also had a large optic nerve. The three semicircular canals of the
inner ear of Carcharodontosaurus saharicus, when viewed from the side,
had a subtriangular outline. This subtriangular inner ear configuration is
present in Allosaurus, lizards, turtles, but not in birds. The semi-"circular"
canals themselves were actually very linear, which explains the pointed
silhouette. In life, the floccular lobe of the brain would have projected into
the area surrounded by the semicircular canals, just like in other non-avian
theropods, birds, and pterosaurs. Pathology
SGM-Din 1, a Carcharodontosaurus saharicus skull, has a circular puncture
wound in the nasal and "an abnormal projection of bone on the antorbital
rim". Discovery, etymology and taxonomic
history In 1924, two teeth were found in the
Continental intercalaire of Algeria, showing what were at the time unique
characteristics, this teeth were described by Depéret and Savornin as
representing a new taxon, which they named Megalosaurus saharicus and later
referred by the same authors to the subgenus Dryptosaurus. Some years later,
paleontologist Ernst Stromer described the remains of a partial skull and
skeleton from Cenomanian aged rocks in the Bahariya Formation of Egypt,
originally excavated in 1914, the remains consisted on a partial skull,
teeth, vertebrae, claw bones and assorted hip and leg bones. The teeth in
this new finding matched the characteristic of those described by
Depéret and Savornin which lead Stromer to conserve the species name saharicus
but found necessary to erect a new genus for this species, Carcharodontosaurus,
for their strong resemblance to the teeth of Carcharodon.
The fossils described by Stromer were destroyed in 1944 during World War II
but a new more complete skull was found in the Kem Kem Formation of Morocco
during an expedition led by paleontologist Paul Sereno in 1995, not
too far from the Algerian border and the locality where the teeth described by
Depéret and Savornin were found, the teeth found with this new skull matched
those described by Depéret and Savornin and Stromer, the rest of the skull also
matched that described by Stromer. This new skull was designated as the neotype
by Brusatte and Sereno who also described a second species of
Carcharodontosaurus, C. iguidensis from the Echkar Formation of Niger, differing
from C. saharicus in aspects of the maxilla and braincase.
The following cladogram after Novas et al., 2013, shows the placement of
Carcharodontosaurus within Carcharodontosauridae.
References External links
Carcharodontosaurus at DinoData Student Identifies Enormous New Dinosaur
December 7 2007 from the Science daily Discovery Channel Videos: Monsters
Resurrected: Biggest Killer Dino