Clades of Chordates

Myxini (Hagfish) Notochord (cartilage rod in place of spinal column) No lower jaw (sucker shaped mouth)

Lamprey (Cephalaspidomorphi) Vertebral column No lower jaw (sucker shaped mouth)

Shark (Chondrichthes) Lower jaw Cartilage skeleton

Bony Fish (Osteichthyes) Swim bladder / lungs Bony skeleton Swim Bladder

Amphibians (Amphibia) Limbs

Reptiles (Reptilia) Amniotic egg Dry, keratinized skin

Mammals (Mammalia) Amniotic egg (replaced by placenta in most mammals) Dry, keratinized skin Hair, mammary glands (milk producing)

Birds (Aves) Amniotic egg Dry, keratinized skin Feathers, beak

Classes of Chordates (Chordate Cladogram) Hagfishes (Myxini) Lampreys (Cephalaspidomorphi) Sharks (Chondrichthyes) Bony Fish (Osteichthyes) Amphibians (Amphibia) Mammals (Mammalia) Reptiles (Reptilia) Birds (Aves) Ancestral Chordate Derived Characters Feathers, Amniotic Egg, Legs, Bony Skeleton, Jaws, Vertebral Column, Hair & Milk, Swim Bladder/Lungs, Keratinized (dry) skin Vertebral Column Jaws Bony Skeleton Swim Bladder/Lungs Legs Amniotic Egg Keratinized (dry) skin Hair & Milk Feathers