Neoselachii

Sawfish ( Pristis perotteti )

As Neoselachii the extant sharks and rays, as well as their immediate ancestors are known. They differ, inter alia, by the strong narrowing of the notochord by the calcification of the vertebrae, the fusion of parts of the belt skeletons and the type of skin teeth of the various Mesozoic elasmobranch groups. Similarities in the structure of spines indicate a descent from the Ctenacanthiformes. The oldest shark that clearly belongs to the Neoselachii is Paleospinax priscus from the Lower Jurassic.

The Neoselachii were 2006 178 genera and 937 species, of which 403 sharks and rays 534 counted. Through new discoveries, the number of species is constantly increasing. 28 species live mainly in fresh water, the rest is marine.

Inside systematics

The Neoselachii have traditionally been classified according to the appearance in sharks and rays. 1996 Neoselachi of de Carvalho and Shirai were divided into two monophyletic taxa independently by morphological features that Galeomorphii ( Galea at Shirai ), which mainly large, the open- water -dwelling sharks are and Squalea to which many ground-dwelling sharks, deep-sea sharks and the rays are. The sharks are thus only a single paraphyletic Formtaxon.

In the meantime, however, there are several molecular studies that confirm a basal dichotomy of sharks and rays. The morphological similarities of squalomorphen sharks with the skates are then created convergent. Because just as the modern sharks let the rays, exactly, since the early Jurassic detected in the fossil record, a derivation of the rays is not supported at the end of a long evolutionary line of Squalea of paleontological data.

In the following tables, each a version of the two different concepts of the inner scheme of Neoselachii be shown.

• Neoselachii Galea Stierkopfhaiartige ( Heterodontiformes )
• Ammenhaiartige ( Orectolobiformes )
• Makrelenhaiartige ( Lamniformes )
• Ground sharks ( Carcharhiniformes )

• Hexanchiformes
• Echinorhiniformes
• Dornhaiartige ( Squaliformes )
• Angel sharks ( Squatiniformes )
• Sägehaiartige ( Pristiophoriformes )
• Skates ( Rajiformes ) Sawfish ( Pristiformes )
• Guitarfish ( Rhinobatoidei )
• Rays i.e.S ( Rajoidei ) Electric ray ( Torpedinidae )
• Skates and rays ( Rajoidea )
• Stingrays ( Myliobatoidea )

• Neoselachii Sharks ( Selachii ) Galeomorphii Stierkopfhaiartige ( Heterodontiformes )
• Ammenhaiartige ( Orectolobiformes )
• Makrelenhaiartige ( Lamniformes )
• Ground sharks ( Carcharhiniformes )

• Hexanchiformes
• Echinorhiniformes
• Dornhaiartige ( Squaliformes )
• Angel sharks ( Squatiniformes )
• Sägehaiartige ( Pristiophoriformes )

• Jitter Roche -behaved ( Torpediniformes )
• Sawfish ( Pristiformes )
• Rajiformes
• Myliobatiformes