The class Chondrichthyes consists of the cartilaginous fishes, including sharks, batoids (rays, skates, guitarfish, and sawfishes), and chimaeras, or ratfishes. A diverse group comprising more than 700 species, Chondrichthyans are found throughout the...

The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage rather than bone. They are divided into two subclasses: Elasmobranchii (sharks, rays and skates)...

Abstract.-The Neoselachii are a monophyletic group including all of the extant sharks and rays. They underwent rapid diversification throughout the Jurassic and Cretaceous, going from low-diversity assemblages of members of extinct orders in the Late Triassic to diverse assemblages containing representatives of most extant...

THE CHIMAEROID fishes enter the fossil record in the Triassic, multiply and diversify to at least 16 genera in the later Mesozoic (Stahl, 1999), and then dwindle during the Cenozoic to only six extant genera (Didier, 1995). Their origin and subsequent evolution have been...