7-450: Squatiniformes is an order of sharks belonging to Squalomorphii . It contains only a single living genus Squatina , commonly known as angelsharks. The oldest genus of the order, Pseudorhina is known from the Late Jurassic of Europe. Three other genera, Cretasquatina , Cretascyllium and Parasquatina are known from Cretaceous fossils from North America and Europe, though
14-592: Is unclear. The earliest records that can be assigned with confidence to the modern genus are known from the Early Cretaceous ( Aptian ) of England. Squalomorphii Squalomorphi is a superorder of cartilaginous fishes , generally characterized by lacking traits such as an anal fin, nictitating membrane , or suborbital shelves in the cranium. Squalomorphii sharks are also called squalea , or squalean sharks . There are about 163 living species in 11 families . Squalean sharks are divided into four orders :
21-496: The Hexanchiformes , Squaliformes , Squatiniformes , and Pristiophoriformes . 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
28-479: The Jurassic period. There are around 120 species in 22 genera, and 6 families. 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
35-513: The late Jurassic period. There are 23 species in 1 genus, and 1 family. 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
42-457: The mid- Jurassic . There are six living species in 4 genera, and 2 families. 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
49-460: The placement of Parasquatina in the order has been questioned. All living and extinct members of the order share a similar body morphology with a highly flattened body with enlarged pectoral and pelvic fins suggestive of a bottom-dwelling ambush predator ecology. Teeth have been assigned to the modern genus from the Late Jurassic onwards, but the actual genus assignment of many of these species
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