''Carcharodontosaurus'' (; ) is a genus of large carcharodontosaurid theropod dinosaur that existed during the

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

age of the Late Cretaceous in Northern Africa. The genus ''Carcharodontosaurus'' is named after the shark genus '' Carcharodon'', itself composed of the Greek (, meaning "jagged" or "sharp") and (, "teeth"), and the

suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form the conjugation of verbs. Suffixes can carry ...

' ("lizard"). It is currently known to have two species: ''C. saharicus'' and ''C. iguidensis''.

History of discovery

In 1924, two teeth were found in the Continental intercalaire of Algeria, showing what were at the time unique characteristics. These teeth were described by Depéret and Savornin (1925) as representing a new taxon, which they named ''Megalosaurus saharicus'' and later categorized in the

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

'' Dryptosaurus''. Some years later, paleontologist Ernst Stromer described the remains of a partial skull and skeleton from

aged rocks in the Bahariya Formation of Egypt (Stromer, 1931); originally excavated in 1914, the remains consisted of a partial skull, teeth, vertebrae, claw bones and assorted hip and leg bones. The teeth in this new finding matched the characteristics of those described by Depéret and Savornin, which led to Stromer conserving the species name ''saharicus'' but finding it necessary to erect a new genus for this species, ''Carcharodontosaurus'', for their similarities, in sharpness and serrations, to the teeth of '' Carcharodon'' ( Great white shark). 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 Group of Morocco during an expedition led by paleontologist Paul Sereno in 1995, near the Algerian border and the locality where the teeth described by Depéret and Savornin (1925) were found. The teeth found with this new skull matched those described by Depéret and Savornin (1925) and Stromer (1931); the rest of the skull also matched that described by Stromer. This new skull was designated as the neotype by Brusatte and Sereno (2007) 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 taxonomy of ''Carcharodontosaurus'' was discussed in Chiarenza and Cau (2016), who suggested that the neotype of ''C. saharicus'' was similar but distinct from the holotype in the morphology of the maxillary interdental plates. However, palaeontologist Mickey Mortimer put forward that the suggested difference between the ''C. saharicus'' neotype and holotype was actually due to damage to the neotype. The authors also identified the referred material of ''C. iguidensis'' as belonging to '' Sigilmassasaurus'' and a non- carcharodontosaurine, and therefore chose to limit ''C. iguidensis'' to the holotype pending future research.

Description

''Carcharodontosaurus'' was one of the longest and heaviest known carnivorous dinosaurs, with an enormous long skull and long, serrated teeth up to long. ''C. saharicus'' reached in length and approximately in body mass, while ''C. iguidensis'' reached in length and in body mass.

Brain and inner ear

In 2001, Hans C. E. Larsson published a description of the

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...

and

endocranium The endocranium in comparative anatomy is a part of the skull base in vertebrates and it represents the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy. Structure Structurally, t ...

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 hindbrain, 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

of ''Carcharodontosaurus saharicus'' – when viewed from the side – had a subtriangular outline. This subtriangular inner ear configuration is present in '' Allosaurus'',

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

s, turtles, but not in birds. The semi-"circular" canals themselves were actually very linear, which explains the pointed silhouette. In life, the

floccular lobe The flocculus (Latin: ''tuft of wool'', diminutive) is a small lobe of the cerebellum at the posterior border of the middle cerebellar peduncle anterior to the biventer lobule. Like other parts of the cerebellum, the flocculus is involved in moto ...

of the brain would have projected into the area surrounded by the semicircular canals, just like in other non-avian theropods, birds, and

pterosaurs Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...

Classification

The following cladogram after Apesteguía ''et al.'', 2016, shows the placement of ''Carcharodontosaurus'' within Carcharodontosauridae.

Paleobiology

Carcharodontosaurus_saharicus_skull_reconstruction

Feeding

A study by Donald Henderson, the curator of dinosaurs at the Royal Tyrrell Museum suggests that ''Carcharodontosaurus'' was able to lift animals weighing a maximum of in its jaws based on the strength of its jaws, neck, and its center of mass.

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.""Acrocanthosauridae fam. nov.," in Molnar (2001). Pg. 342.

References

External links

Student Identifies Enormous New Dinosaur December 7 2007 from the Science daily

{{Taxonbar, from=Q14431 Carcharodontosaurids Late Cretaceous dinosaurs of Africa Cenomanian genus extinctions Bahariya Formation Fossil taxa described in 1931 Taxa named by Ernst Stromer Apex predators Cenomanian life