Ground sharks, like this blacknose shark, have a nictitating membrane which can be drawn over the eye to protect it.

Carcharhiniformes /kɑːrkəˈrnɪfɔːrmz/, commonly known as ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and requiem sharks.

Members of this order 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 conventional groups are not monophyletic.

The oldest members of the order appeared during the Middle-Late Jurassic, which have teeth and body forms that are morphologically similar to living catsharks.[1] Carchariniformes first underwent major diversification during the Late Cretaceous, initially as mostly small-sized forms, before radiating into medium and large body sizes during the Cenozoic.[2][3]

Families

Eschmeyer's Catalog of Fishes classifies the Carcharhiniformes into two suborders and nine families:[4]

Fossil genera

The following fossil genera of Carcharhiniformes are also known:[5]

References

Further reading

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