Order Hexanchiformes The order Hexanchiformes is a very small and primitive order consisting of cow sharks and frilled sharks. These sharks have only 1 dorsal fin, 6-7 gill slits, and no
nictitating membrane on the eyes. Cow sharks are fairly large and stocky, while frilled sharks are smaller and have eel-like bodies. The oldest fossils from this order can be dated back to the mid-
Jurassic. There are six living species in 4
genera, and 2 families. • Family
Hexanchidae (Cow sharks) • Family
Chlamydoselachidae (Frilled sharks)
Order Squaliformes The order Squaliformes is a large, ancient order of sharks. Sharks from this order have two dorsal fins -usually with spines-, no anal fin, and no nictitating membrane on the eyes. Squaliform sharks are extremely variable in size and shape, and can be found in most marine habitats throughout the world. Like Hexanchiformes, members of Squaliformes can be found as early as the Jurassic period. There are around 120 species in 22 genera, and 6 families. • Family
Centrophoridae (Gulper sharks) • Family
Dalatiidae (Kitefin sharks) • Family
Etmopteridae (Lantern sharks) • Family
Oxynotidae (Rough sharks) • Family
Somniosidae (Sleeper sharks) • Family
Squalidae (Dogfish sharks) ===Order
Echinorhiniformes=== • Family
Echinorhinidae (bramble sharks)
Order Squatiniformes The order Squatiniformes is a small order of highly specialized and recognizable sharks called angel sharks. The angel sharks have flattened bodies and broad pectoral fins, as well as camouflaged coloration. These characteristics allow angel sharks to blend in with their
benthic environments. Members of Squatiniformes have been found since the late Jurassic period. There are 23 species in 1 genus, and 1 family. • Family
Squatinidae (Angel sharks)
Order Pristiophoriformes The order Pristiophoriformes is a small order of unique sharks called sawsharks. Sawsharks have a long snout covered in teeth, between 5-6 gill slits, and no anal fin. They also have a pair of barbels usually located halfway down the snout. Sawsharks are frequently confused with sawfish, which are members of the ray order
Pristiformes. Sawsharks can be discerned from sawfish thanks to their
lateral gill slits, which differ from the sawfish's
ventral gill slits. These sharks can mostly be found in deep benthic environments. Fossils of members of this order have been found since the late Jurassic period. There are 8 species in 2 genera, and 1 family. • Family
Pristiophoridae (Saw sharks) ==References==