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