Osteichthyes, also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes and the extinct placoderms and acanthodians, which have endoskeletons primarily composed of cartilage. The vast majority of extant fish are members of Osteichthyes, being an extremely diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species. It is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates.
Osteichthyes
Guiyu oneiros, the earliest known bony fish, lived during the Late Silurian, 425 million years ago. It has a combination of both ray-finned and lobe-finned features.
The ocean sunfish is one of the heaviest bony fish in the world.
Image: Carassius carassius
Vertebrates are deuterostomal animals with bony or cartilaginous axial endoskeleton — known as the vertebral column, spine or backbone — around and along the spinal cord, including all fish, amphibians, reptiles, birds and mammals. The vertebrates consist of all the taxa within the subphylum Vertebrata and represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described.
Fossilized skeleton (cast) of Diplodocus carnegii, showing an extreme example of the backbone that characterizes the vertebrates.
Gill arches bearing gills in a pike
The early vertebrate Haikouichthys
Acanthostega, a fish-like early labyrinthodont.
