16 Emergent Chordates I | emergentearth

top of page

an emergent

website design

peter jay stein, md, ma

atmosphere

asthenosphere

lithosphere

regolith

biosphere

hydrosphere

emergentsong.com

This 54 page synopsis of the evolution

of the Earth, the origin and progression of life, and the

emergence of humans as descendants of the hominin lineage, divides the last 4.57 billion years into progressively overlapping, imagistic, time segments, to outline our place in biological existence.

magnetosphere

ionosphere

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:

full cranium and rudimentary vertebrae

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