שאלה | 60. The “new head” hypothesis:

60. The “new head” hypothesis:

		Is a theory of how development of primitive chordates into vertebrates involved development of sensory organs from neural crest and placodes
		Is a new theory of how the head developed in primitive chordates by secondary neurulation
		Is a theory of how primary neurulation led to development of the jaws
		Is a theory of how advanced vertebrates developed sophisticated brains which come from neural placodes