| Euselachii Temporal range: [1] | |
|---|---|
 | |
| Tiger shark | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Infraclass: | Euselachii Hay, 1902 |
| Orders | |
|
See text | |
Euselachii are an infraclass of a class of cartilaginous fish. This group includes sharks and rays.[2][3][4]
Taxonomy
Of the 14 orders that compose Euselachii, 8 belong to the sharks, 6 to the rays, without an intermediate taxon separating sharks of rays. For this reason, some authors have separated Euselachii in two:
super-order Selachimorpha corresponding to orders of sharks; super-order Rajomorphii corresponding to the orders of rays, torpedoes, sawfish and guitar fish. For those who do not recognize these two super-orders, Euselachii therefore has for synonyms Pleurotremata, Selachimorpha and Rajomorphii.
Reproduction
Both oviparity and viviparity are found in Euselachii. Around 70% of sharks are viviparous,[5] including some members of Carcharhiniformes such as requiem sharks and hammerhead sharks, while the remaining 30% of sharks as well as all rays are either oviparous or ovoviviparous.
Physical appearance
There was a recent discovery that a Palaeozoic chondrichthyan (carcharopsis) was found to no longer resemble the "triple-layer" tooth structure that the modern day chondrichthyan sharks model.
List of orders
- Euselachii
- Superorder Selachimorpha (sharks):
- Carcharhiniformes - ground sharks
- Heterodontiformes - bullhead sharks
- Hexanchiformes - six- and sevengill sharks
- Lamniformes - mackerel sharks
- Orectolobiformes - carpet sharks
- Pristiophoriformes - saw sharks
- Squaliformes - dogfish
- Squatiniformes - angel sharks
- Superorder Rajomorphii or Batoidea (rays, torpedoes, sawfish and guitar fish):
- Myliobatiformes - stingrays
- Pristiformes - sawfish
- Rajiformes - skates, sometimes in addition to guitarfish and wedgefish
- Rhiniformes - wedgefish (frequently included in Rajiformes)
- Rhinobatiformes - guitarfish (frequently included in Rajiformes)
- Torpediniformes - electric rays
- Euselachii incertae sedis[6]
- †Ctenacanthiformes Cappetta 1988
- Superorder Selachimorpha (sharks):
References
- ↑ "Infraclass Euselachii Hay 1902". Fossilworks.org.
- ↑ Nelson, J. S. (2006). Fishes of the World (4 ed.). Hoboken, NJ: John Wiley & Sons. p. 49. ISBN 978-0-471-25031-9.
- ↑ "Euselachii". Integrated Taxonomic Information System. Retrieved 21 May 2018.
- ↑ "Fish glossary". FishBase.
- ↑ "Mating and Reproduction of Sharks", Shark Foundation
- ↑ J. A. Long. 2011. The Rise of Fishes: 500 Million Years of Evolution (Second Edition) 1-287 [G. Lloyd/G. Lloyd/M. Uhen]