Vertebrates evolved from primitive forms of which creature?
eukaryotes
gastropods
cephalopods
chordates
Vertebrates evolved from primitive chordates. This occurred about 550 million years ago. The earliest vertebrates may have been jawless fish, like the hagfish in Figure below . Vertebrates evolved a backbone to replace the notochord after the embryo stage. They also evolved a cranium, or bony skull, to enclose and protect the brain.