Carcharodontosaurus

***Carcharodontosaurus*** (meaning "shark-toothed lizard") was one of the largest theropod carnivores alongside *Saurophaganax* and *Bahariasaurus;* that are similar in size or larger than well-known theropods Tyrannosaurus; although possibly smaller than *Spinosaurus* and *Giganotosaurus*. It was likely the second largest of the carcharodontosaurid theropod family, and it lived in North Africa. C. saharicus grew to be about 12 – 13.5 meters (39–44 feet) long, about 3.5-4 (11.5-13 feet) tall at the hips and about 6.5 - 8 tonnes (7.2-8.8 tons) in weight.

Paleontologists once thought that *Carcharodontosaurus* had the longest skull of any of the theropod dinosaurs. However, the premaxilla and quadrate bones were missing from the original African skull, which led to misinterpretation of its actual size by researchers. A more modest length of five feet, three inches (1.6 meters) has now been proposed. Thus, the honor of the largest theropod skull is now in question.

*Carcharodontosaurus* fossils were first found by Charles Depéret and J. Savornin in North America in 1756. Originally called *Megalosaurus saharicus*, its name was changed in 1831 by Ernst Stromer von Reichenbach to that used today. These first fossils of *Carcharodontosaurus* were destroyed during World War II In an allied fighter bombing raid who destroyed the museum and every last piece of Carcharodontosaurus. However, cranial material from a *Carcharodontosaurus* was again discovered in North Africa in 1914 by paleontologist Paul Sereno. Stephen Brusatte and Paul Sereno (2005) reported a second species of *Carcharodontosaurus* differing from *C. saharicus* in some aspects of the maxilla and braincase. The new species, which was discovered in Niger, is called *C. iguidensis* but recently new studies have brought to light that this dinosaur was a chimera.

## 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 meters (39 and 44 ft) and weight estimates between 6.2 to 15.1 metric tons (6.8 to 16.6 short tons). In 2016 Molina-Pérez & Larramendi gave a length of 12.8 meters (42 ft) and a weight of 7.8 metric tons (8.6 short tons) for the neotype of *C. saharicus*, and a length of 11 meters (36 ft) and a weight of 5.2 metric tons (5.7 short tons) for a referred tooth of *C. iguidensis*.

*Carcharodontosaurus* were carnivores, with enormous jaws and long, serrated teeth up to eight inches long. A skull length of about 1.42–1.6 m (4.7–5.2 ft) has been restored for the neotype of *C. saharicus.* Currently, the largest-known theropod skull belongs to another huge carcharodontosaurid dinosaur, the closely related *Giganotosaurus* (with skull length estimates up to 1.95 m (6.4 ft)) but this has been disputed. Gregory S. Paul estimates *Carcharodontosaurus iguidensis* at 10 meters (33 ft) and 4 metric tons (4.4 short tons).

### Brain and inner ear

n 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 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 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.

## *Carcharodontosaurus* in The Amazing Dinosaur Adventure

*Carcharodontosaurus* from *The Mysterious Island*