NO BRAIN
NOTOCHORD PERSIST THROUGHOUT LIFE
SUBPHYLUM
UROCHORDATA
CEPHALOCHORDATA
NOTOCHORD REPLACED BY VERTIBRAL COLOUMN
SUBPHYLIM
Subtopic
AGNATHA
2 CLASSES
OSTRACODERMI
CYCLOSTOMATA
GNATHOSTOMATA
2 SUPERCLASSES
PISCES
3 CLASSES
PLACODERMI
CHONDRICHTHYES
OSTEICHTHYES
TETRAPODA
4 CLASSES
AMPHIBIA
REPTILIA
AVES
MAMMALIA