Carcharodontosauridae

Carcharodontosaurids Temporal range: Late Jurassic–Late Cretaceous,
Reconstructed Carcharodontosaurus skull, Science Museum of Minnesota
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	†Carcharodontosauria
Family:	†Carcharodontosauridae Stromer, 1931
Type species
†Megalosaurus saharicus (Deperet & Savornin, 1925)
Subgroups
†Acrocanthosaurus †Altispinax? †Concavenator †Eocarcharia †Kelmayisaurus †Lajasvenator †Sauroniops †Shaochilong †Siamraptor? †Taurovenator †Veterupristisaurus †Carcharodontosaurinae †Carcharodontosaurus †Giganotosaurini †Giganotosaurus †Mapusaurus †Tyrannotitan
Synonyms
Acrocanthosauridae Molnar, 2003

Carcharodontosaurids (from the Greek καρχαροδοντόσαυρος, carcharodontósauros: "shark-toothed lizards") were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, which, in modern paleontology, indicates a clade within Carnosauria. Carcharodontosaurids include some of the largest land predators ever known: Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan all rivaled or possibly slightly exceeded Tyrannosaurus in length. A 2015 paper by Christophe Hendrickx and colleagues gives a maximum length estimate of 14 metres (46 ft) for the largest carcharodontosaurids, while the smallest carcharodontosaurids were estimated to have been at least 6 metres (20 ft) long.

Evolution

Restoration of the crushed skull of Concavenator

Along with the spinosaurids, carcharodontosaurids were the largest predators in the early and middle Cretaceous throughout Gondwana, with species also present in North America (Acrocanthosaurus), Europe (Concavenator) and Asia (Shaochilong). Carcharodontosaurids range throughout the Cretaceous from the Barremian (127-121 million years ago) to the Turonian (93-89 million years ago). Past the Turonian, they might have been replaced by the smaller abelisaurids in Gondwana and by tyrannosaurids in North America and Asia. According to Fernando Novas and colleagues, the disappearance of not only carcharodontosaurids but also spinosaurids and other fauna in both Gondwana and North America seem to indicate that this faunal replacement occurred on a global scale. While some teeth and a maxilla discovered in Maastrichtian deposits of Brazil have been assigned to carcharodontosaurids, possibly extending their range, this identification has been subsequently rejected and the material assigned to abelisaurids after better examination. In December 2011, Oliver W. M. Rauhut described a new genus and species of carcharodontosaurid from the Late Jurassic (late Kimmeridgian to earliest Tithonian faunal stage, about 154-150 million years ago) of Tendaguru Formation, southeastern Tanzania. This genus, Veterupristisaurus represents the oldest known carcharodontosaurid.

Classification

The family Carcharodontosauridae was originally named by Ernst Stromer in 1931 to include the single newly discovered species Carcharodontosaurus saharicus. A close relative of C. saharicus, Giganotosaurus, was added to the family when it was described in 1995. Additionally, many paleontologists have included Acrocanthosaurus in this family (Sereno et al. 1996, Harris 1998, Holtz 2000, Rauhut 2003, Eddy & Clarke, 2011, Rauhut 2011), though others place it in the related family Allosauridae (Currie & Carpenter, 2000; Coria & Currie, 2002). Carcharodontosaurids are characterized by the following morphological characters : Dorsoventral depth of anterior maxillary interdental plates more than twice anteroposterior width, squared, sub-rectangular anterior portion of the dentary, teeth with wrinkled enamel surfaces, presence of four premaxillary alveoli and a premaxillary body taller than long in lateral aspect, opisthocoelous cervical vertebrae with neural spines more than 1.9 times the height of the centrum, large, textured rugosities on the lacrimal and postorbital formed by roofing and forming broad orbital shelves, and a proximomedially inclined femoral head. With the discovery of Mapusaurus in 2006, Rodolfo Coria and Phil Currie erected a subfamily of Carcharodontosauridae, the Giganotosaurinae, to contain the most advanced South American species, which they found to be more closely related to each other than to the African and European forms. Coria and Currie did not formally refer Tyrannotitan to this subfamily, pending a more detailed description of that genus, but noted that based on characteristics of the femur, it may be a gigantosaurin as well.

Size comparison of seven carcharodontosaurids

In 1998 Paul Sereno defined Carcharodontosauridae as a clade, consisting of Carcharodontosaurus and all species closer to it than to either Allosaurus, Sinraptor, Monolophosaurus, or Cryolophosaurus. Therefore, this clade is by definition outside of the clade Allosauridae. The cladogram below follows the analysis of Brusatte et al., 2009.

Carcharodontosauridae	Neovenator Acrocanthosaurus Eocarcharia Shaochilong Tyrannotitan Carcharodontosaurus Giganotosaurinae Giganotosaurus Mapusaurus

Cladogram after Ortega et al., 2010

Carcharodontosauridae	Eocarcharia Concavenator Acrocanthosaurus Shaochilong Tyrannotitan Carcharodontosaurus Giganotosaurus Mapusaurus

Cladogram after Novas et al., 2013

	Allosaurus Carcharodontosauridae Neovenator Eocarcharia Concavenator Acrocanthosaurus Shaochilong Carcharodontosaurinae Carcharodontosaurus Giganotosaurini Tyrannotitan Mapusaurus Giganotosaurus

Mounted Acrocanthosaurus skeleton (NCSM 14345) at the North Carolina Museum of Natural Sciences.

The placement of Acrocanthosaurus is unclear, with most researchers favoring Carcharodontosauridae and others favoring Allosauridae. In 2011, a redescription of Kelmayisaurus by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found it to be valid genus of Carcharodontosauridae. A phylogenetic analysis of Tetanurae recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy with Eocarcharia and a clade comprising more derived carcharodontosaurids. Bahariasaurus has also been proposed as a carcharodontosaurid, but its remains are too scarce to be certain.

Carcharodontosaurids have been proposed as more closely related to abelisaurids, as opposed to the allosaurids. This is due to these two clades sharing some cranial features. However, these similarities appear to derive from parallel evolution between these two groups. A larger number of cranial and postcranial characters support their relationship with allosaurids.

External links

• Carcharodontosauridae/Abelisauridae
• Carcharodontosauridae/Abelisauridae 2