Fish Bio Review #1

lamprey and hagfish are living representatives

• Notochord
• Hollow, dorsal nerve chord
• Pharyngeal slits

Jawed fishes

Order Myxiniformes -  modern hagfish

Order Petromyzontiformes - modern lamprey

Class Cephalaspidomorphi = ancestor to lamprey??

Class Pteraspidomorphi = ancestor to hagfish??

• Ostracoderms now extinct

Myxinidae

Family Petromyzontidae

Class Placodermi - plate-skinned (extinct)

• Class Acanthodii - spiny sharks (extinct)
• Class Sarcopterygii – lobed-fin fishes

Class Chondrichthys - sharks, skates, rays

Class Actinopterygii - ray-finned fishes

Dunkleosteus- Head and shoulder girdles with dermal bony plates joined by Craniovertebral joint which allowed it to move.

Arthrodire- "jointed neck"

Acanthoidian- extict class of fish

More closely related to modern day bony fish than sharks, even though skeleton was mostly made of cartilage.

• Terminal mouth
•  Fins broad-based and stiff,long radial elements  
•  No anal find.    
•  Caudal fin is homocercal    
• Body supported by notochord only      
• Often spines in front ofdorsal, pectoral, and pelvic

• -Terminal mouth
• - Fins flexible and mobile
• -Anal fin     
• -Caudal fin heterocercal
• -Body supported by notochord
• with neural arches
• - Spines on dorsal fin

• 1. Jaws: ventral mouth with protrusible upper jaw
• 2. Dentition: tooth replacement system
• 3. Fins: ceratotrichia supporting the fins
• 4. Vertebrae: calcified vertebrae instead of notochord

Subdivision Selachii (sharks - 9 Orders)

Subdivision Batoidea (rays - 4 Orders)