From Chordates to Fish To Mammals
adapted from Biology, p.653-654
PHYLUM: Chordates
CLADE: CRANIATES
vertebrata
urochordata
(tunicates)
cephalochordata
(amphioxus)
SUB-PHYLUM
myxiniformes
(hagfishes: cranium, but no vertebrae)
petromyzontiformes
(lampreys)
CLASS I
gnathostomes
(placoderms)
chondrichthyes
(cartilaginous)
bony fishes
mammals
birds
amphibians
JAWS EVOLVE NEXT:
BONE EVOLVES NEXT:
JAWLESS VERTEBRATES EVOLVE NEXT:
LIMBS AND LUNGS EVOLVE NEXT:
reptiles
AMNIOTIC EGG EVOLVES NEXT:
CLASS 2
CLASS 3
CLASS 4
CLASS 5
CLASS 6
CLASS 7
CLASS 8
extinct, jawed, armored FISHES, paired fins
armored, bony head plates, thick trunk scales, no fins, Devonian extinct
SUB-PHYLUM
SUB-PHYLUM
SUB-PHYLUM:
full cranium and rudimentary vertebrae
tetrapod
tetrapod
tetrapod
tetrapod

SIXTEEN
Emergent Chordates I
"...Agnathan or jawless vertebrates, such as lampreys, occupy a critical phylogenetic position between the gnathostome or jawed vertebrates and the cephalochordates, represented by amphioxus..." (Developmental Biology, 3/1999, vol. 207 (1), p. 26); "...The evolution of jaws allowed gnathostomes to become effective predators and probably accounted for much of their subsequent success..." (Developmental Biology, 12/2004, vol. 276, p. 225).
agnathans - ostracoderms
CARTILAGE EVOLVES NEXT:
jawless fish
jawed fish
cartilagenous fish
bony fish
amphibians
reptiles
birds
mammals
8 CLASSES