Carcharodontosaurus

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Saurischia

Family: Carcharodontosauridae

Genus: Carcharodontosaurus

Species: Carcharodontosaurus saharicus

Introduction

Carcharodontosaurus was a large carnivorous dinosaur living in the Late-Cretaceous forests and scrub of what is now Northern Africa. The species evolved from an ancestor that spread in the Jurassic and diverged into different species in the Late Jurassic or Early Cretaceous.

In the Triassic period, the continents were united in a single land mass known as Pangaea. Dinosaurs evolved in this period and spread across the globe. In the Jurassic and Cretaceous, Pangaea split apart under geophysical forces and gave rise to two supercontinents, Laurasia in the north and Gondwana in the south. Species that spread in the Jurassic were isolated and began to diverge into new species.

The two species in the genus Carcharodontosaurus both evolved in Gondwana, with other members of their group becoming the dominant terrestrial predators on the supercontinent. Carcharodontosaurus and related species have been important in the effort to determine the evolution and spread of the theropods before and after the break-up of Pangaea.

Classification

Scientists utilize two primary methods to divide animals into different groups. Linnaean taxonomy, or “systematics,” groups organisms hierarchically according to overall physical similarity, while “cladistics” creates groups called “clades” intended to reflect the evolutionary relationships between species.

Taxonomic analysis places Carcharodontosaurus into the order Saurischia because of the lizard-like configurations of its pelvis. From there, the species is placed within the suborder Theropoda, which were bi-pedal carnivores, and the infraorder Carnosauria, containing theropods with large eyes and relatively narrow skulls. The family Carcharodontosauridae contains a number of genera united by similar skull and leg features. However, over the years some paleontologists debated the placement of certain genera, particularly the Acrocanthosaurus. While, because it was found to be closely related to the Allosaurus, some scientists argued for the genus to belong to the Allosauridae family, others made the case that it was more similar to the Carcharodontosaurus, warranting its placement in the Carcharodontosauridae family.

Cladistics also places this species within Carnosauria, a clade that diverged from the theropods just at the division of the Avetherapoda, the dinosaurs most closely related to birds. The Carnosauria are defined by the presence of large openings in the skull and large nasal cavities. The family Carcharodontosauridae is also a clade that includes the African species and at least one Asian and one North American relative, all defined by features of the skull.

Anatomy

Carcharodontosaurus was one of the largest predators found to date, reaching lengths of between 11 and 13.5 meters (36–44.2 ft) and standing at least 3.6 meters (11.8 ft) at the hip. Paleontologists estimate that the animal could have weighed between 6.5 and 8 metric tons (14,330–17,636 lbs). C. saharicus was smaller than its close relative C. iguidensis, which had a larger maxilla and braincase.

The animal was bipedal, with long powerful legs terminating in three-toed, clawed feet. Its long muscular tail was reinforced by thick bony struts. The neck had enlarged vertebrae, presumably anchoring muscles that aided in capturing or killing prey. Paleontologists are uncertain about the animal's skin covering, but it most likely included mosaic scales similar to tissue impressions found for other dinosaurs.

Carcharodontosaurus had a broad skull with a shorter muzzle than other groups of theropods. The skull measured about 1.6 meters (5.2 ft) long, and the animal had rows of teeth that could grow as long as 30 centimeters (11.8 in). Carcharodontosaurus had forward-facing eyes and a large muzzle with wide nostrils, presumably endowing the animal with enhanced olfactory capabilities.

Intelligence

While Carcharodontosaurus was similar in size to the tyrannosaurid predators of Laurasia, its skull cavity had only half the capacity, making Carcharodontosaurus significantly less intelligent than its North American relatives. Given the animal's brain size, Carcharodontosaurus was probably similar in intelligence to a large lizard or crocodilian, significantly less intelligent than modern mammalian predators.

African crocodiles, which have a similar brain size to the Carcharodontosaurus, remain one of the leading predators in Africa by using instinct where other predators use evaluation and more advanced intelligence. Thus, increased brain size or intelligence does not guarantee greater success as a predator.

Reproduction and Population

Paleontologists know little about the reproductive behavior of the carnosaurs. It is assumed, given the construction of the animal's pelvis, that Carcharodontosaurus and its relatives laid relatively small eggs and therefore had small young. Animals of this size would generally have been unable to brood their eggs by sitting on the nest and may therefore have covered their nests in vegetation, which shields the eggs from the sun and gives off heat and moisture as the vegetation decomposes.

Carcharodontosaurus is known only from a few specimens and it is uncertain whether males and females of the species differed in size or appearance, a phenomenon called sexual dimorphism. It is also uncertain whether Carcharodontosaurus was a solitary breeder or whether males and females cooperated in rearing young.

Diet

Judging from its dentition, Carcharodontosaurus was a predator and most likely specialized in large prey. Enlarged nasal cavities and forward-facing eyes are the hallmarks of predators that rely on both vision and scent to find prey. Given its size, it is likely that Carcharodontosaurus hunted herbivorous dinosaurs rather than attempting to capture the smaller mammals, amphibians, and reptiles that shared its habitat.

The enlarged neck vertebrae on Carcharodontosaurus may have been an adaptation allowing the animal to hold on to struggling prey. Alternatively, these muscles could also have allowed the animal to rip flesh from a carcass by pulling its head from side to side once its teeth were buried. Africa had a few sauropods living alongside Carcharodontosaurus and these may have formed an important part of the animal's diet.

Behavior

Given the scarcity of Carcharodontosaurus fossils, paleontologists believe that the animal was a solitary predator. Analyses of the animal's leg structure indicate that Carcharodontosaurus would not have been suited to long chases or high-speed pursuit. The animal most likely remained concealed in vegetation to ambush prey, or it may have specialized in preying on juvenile or elderly animals.

Some paleontologists have suggested that large theropods, like Carcharodontosaurus and its North American cousin Tyrannosaurus, often fed on carrion, using their advanced sense of smell to locate the bodies of recently deceased animals and then relying on size to steal carcasses from smaller predators. Carcharodontosaurus may have utilized an opportunistic strategy, eating carrion when available but also stalking live prey.

Habitat and Other Life Forms

Late-Cretaceous Africa was an environment that gave rise to many large dinosaurs. The habitat had more moisture than in the modern period, with large rivers, lakes, and flood plains covering vast areas. The primary types of vegetation were gymnosperms, like conifers and cycads, and pteridophytes, including ferns and other spore bearing plants.

In addition to dinosaurs, Cretaceous Africa had a wide variety of small mammals, reptiles, and amphibians. Carcharodontosaurus was one of the largest purely terrestrial predators, but the larger, semi-aquatic predator Spinosaurus also hunted in the same area, reaching very large sizes. There were also several species of ceratosaurs, another group of smaller theropods living in Africa, including Deltadromeus.

Cretaceous Africa was home to a variety of sauropods, descendants of the giant herbivores that dominated the Jurassic. Aegyptosaurus and Brachiosaurus were two of the large sauropods that lived in mid-Cretaceous Africa. There were also a variety of ankylosaurs. Large iguanodontids, like Lurdusaurus and Iguanodon, were also present in Africa in the early to mid-Cretaceous period.

Research

The first Carcharodontosaurus fossils were discovered in 1927 by paleontologists Charles Deperet and J. Savornin, working in fossil beds in Algeria. Paleontologist Ernst Stromer von Reichenboch later named the genus Carcharodontosaurus after the shark-like shape of the animal's teeth. Paleontologist Paul Sereno conducted one of the first major reformulations of the genus after his discovery of fossils from the species C. iguidensis during a 1997 dig in Nigerian fossil beds.

Descriptions of C. iguidensis and a revision of the genus were conducted by paleontologist Steve Brusette and colleagues from the University of Bristol in 2007. Also reported were discoveries about the species’ braincase and subsequent analyses of the intelligence of the dinosaur in relation to other carnosaurs.

In the early twenty-first century, scientists continued to study dinosaurs belonging to genera within the family Carcharodontosauridae to learn more about how they were different from larger carnivores from other areas, particularly the well-known Tyrannosaurus. Paleontologists analyzed differences in teeth, skulls, and neck muscles to discern how the dinosaurs had evolved to take down prey. They also analyzed why the Carcharodontosaurus and related large carniverous dinosaurs seemed to dominate in the Southern Hemisphere.

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