Galeomorphii

Galeomorphi
Temporal range: Jurassic–Recent[1]
Great white shark
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Galeomorphi
Orders
Radiation of cartilaginous fishes, including the Galeomorphi. Derived from work by Michael Benton, 2005.[2]

Galeomorphii is a superorder of cartilaginous fishes which includes all modern sharks except the dogfish and its relatives. They are sometimes called galea or galean sharks. There are about 300 living species in 23 families. Galean sharks are divided into four orders: the Heterodontiformes, Orectolobiformes, Lamniformes, and Carcharhiniformes

Classification

Order Heterodontiformes

Main article: Bullhead sharks

The bullhead sharks are a small order of basal modern sharks (Neoselachii). All are relatively small, with the largest species being just 150 centimetres (59 in) in adult length. They are bottom feeders in tropical and subtropical waters. They appear in the fossil record in the Early Jurassic, well before any of the other galean sharks. However, they have never been common, and it is likely their origin lies even further back.

There are nine living species in a single genus, Heterodontus and a single family.

Order Orectolobiformes

Carpet sharks are another small order of sharks, so called because many members have ornate patterns reminiscent of carpets. Sometimes the term "carpet shark" is used interchangeably with wobbegong, which are a subgroup of the order. Carpet sharks have two dorsal fins, without spines, and a small mouth that is forward of the eyes. Many have barbels and small gill slits, with the fifth slit overlapping the fourth. The upper lobe of the caudal fin tends to be mostly in line with the body, while the lower lobe is poorly developed.

The order has around 43 species in seven families and 13 genera:

Order Lamniformes

Main article: Mackerel shark

Mackerel sharks are an order which includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark. Members of the order are distinguished by possessing two dorsal fins, an anal fin, five gill slits, eyes without nictitating membranes, and a mouth extending behind the eyes. Mackerel sharks may also refer specifically to the family Lamnidae.

The order includes seven families and sixteen living species:

Order Carcharhiniformes

Main article: Ground shark

Ground sharks are the largest order of sharks, and include a number of common types such as the blue shark, catsharks, swellsharks and sandbar sharks. Members of the orders are characterized by the presence of a nictitating membrane over the eye, two dorsal fins, an anal fin, and five gill slits. The families in the order Carcharhiniformes are expected to be revised; recent DNA studies show that some of the traditional groups are not monophyletic.

The order includes eight families and over 270 species:

References

  1. ↑ Stevens, J. & Last, P.R. (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 60. ISBN 0-12-547665-5.
  2. ↑ Benton, M. J. (2005) Vertebrate Palaeontology, Blackwell, 3rd edition, Fig 7.13 on page 185.

Further reading

External links

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