[[2]]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[3], 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.
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[4]
- {{extinct}}Ctenacanthiformes Cappetta 1988
References
1. ^{{cite web |title=Infraclass Euselachii Hay 1902 |url=http://fossilworks.org/bridge.pl?taxon_no=150723&action=taxonInfo |website=Fossilworks.org}}
2. ^{{cite web|title=Fish glossary|url=https://www.fishbase.de/glossary/Glossary.php?q=Euselachii |work=FishBase}}
3. ^"Mating and Reproduction of Sharks", Shark Foundation
4. ^J. A. Long. 2011. The Rise of Fishes: 500 Million Years of Evolution (Second Edition) 1-287 [G. Lloyd/G. Lloyd/M. Uhen]
5. ^1 {{Cite book| last = Nelson| first = J. S.| title = Fishes of the World| authorlink = Joseph S. Nelson| location = Hoboken, NJ| date = 2006| edition = 4| publisher = John Wiley & Sons| isbn = 978-0-471-25031-9| page=49}}