Carcharodontosauridae
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 Giganotosaurus skeleton at the Australian Museum, Sydney
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Carcharodontosaurids (from the Greek Carcharodontosauros: "shark-toothed lizards") were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria. In 2005 Paul Sereno defined it as the clade consisting of Carcharodontosaurus saharicus and all species closer to Carcharodontosaurus than to either Allosaurus fragilis, Sinraptor dongi or Passer domesticus. This clade is by definition outside of the clade Allosauridae. Carcharodontosaurids included some of the largest land predators ever known: Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan all rivaled or exceeded T. rex in size.
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[edit] Evolution
Along with spinosaurids, carcharodontosaurids were the largest predators in the Early and Middle Cretaceous throughout Gondwana and Europe (Neovenator), and also in North America (Acrocanthosaurus). Their ages range from the Barremian (127-121 million years ago) to the Cenomanian (99-93 million years ago). It's possible they were also present during the Turonian (93-89 million years ago).
However, past the Turonian, there seem to be no signs of the presence of these animals anywhere on the world. They were replaced by the smaller abelisaurids in Gondwana and by tyrannosaurids in North America. According to Fernando Novas (Novas et al 2005) 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.
[edit] Taxonomy
[edit] Classification
- Family CARCHARODONTOSAURIDAE
- Genus Neovenator
- Genus Acrocanthosaurus
- Genus Carcharodontosaurus
- Subfamily GIGANOTOSAURINAE
- Genus Mapusaurus
- Genus Tyrannotitan
- Genus Giganotosaurus
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), though others place it in the related family Allosauridae (Currie & Carpenter, 2000; Coria & Currie, 2002). Neovenator may also be a member of the Carcharodontosauridae (Rauhut, 2003; Holtz et al., 2004).
With the discovery of Mapusaurus in 2006, Coria and Currie[1] erected a subfamily of Carcharodontosauridae, 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.
[edit] Phylogeny
Possible phylogeny for this clade (From Mickey Mortimer's Theropod Database, modified after Coria & Currie 2006):
Carcharodontosauridae |--Neovenator `--+--Acrocanthosaurus `--+?-"Megalosaurus" inexpectatus |--Carcharodontosaurus `--Giganotosaurinae |--Mapusaurus |--Tyrannotitan `--Giganotosaurus
The placement of Acrocanthosaurus is unclear, with some researchers favoring Carcharodontosauridae and others favoring Allosauridae. Bahariasaurus has also been proposed as a carcharodontosaurid, but it's remains are too scarce to be certain. It appears to be synonymous with the ceratosaur Deltadromeus.
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 (see link below). 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.
[edit] References
- ^ Coria RA & Currie PJ. (2006): A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina. Geodiversitas: Vol. 28, #1, pp. 71-118
- Novas, de Valais, Vickers-Rich and Rich, 2005.A large Cretaceous theropod from Patagonia, Argentina, and the evolution of carcharodontosaurids. Naturwissenschaften.
