Superclass Pisces

jawless vertebrates (suckers)

• No paired appendages
• Cartilage Skeleton
• single nostril on top of head (monorhinous)

Ostracoderms are the oldest known fossil vertebrates, covered externally by bony plates. (No fins)

• Petromyzontia (Lampreys)
• Myxinoidea (Hagfish)

first jawed vertebrates.

• Heavy bony armor
• paired fins developing

It was known only from fossils, some investigators consider then a subclass of Chondrichthyes.

cartilagenous jawed fishes.

• upper jaw not attached to braincase
• teeth from placoid scales
• internal ferilization with claspers
• most ovoviviparous

• Elasmobranchii
• Holocephali

• order squaliformes (True shark)
• order Rajiiformes (Skates and rays)

order Chimaeriformes (Ratfishes and chimaeras)

spiny sharks (extinct) 3-5 inches long

some investigators group these with Osteichthyes, some with Placodermi, and some say they stand apart.

Bony fishes; have jaws, paired appendages, and dermal scales.

• Sarcopterygii (lobe finned fishes)
• Actinopterygii (ray-finned fishes)

• Order Crossopterygii
• Order Dipnoi ( Lung fishes )

• Chondrostei (Sturgeons and paddlefishes)
• Neopterygii ( Gars and bowfin, modern ray finned fishes)