What features in the structure of ancient amphibians allowed them to develop land as a new habitat?

1) The appearance of lever limbs necessary for movement.
2) The appearance of one cervical vertebra, which allowed amphibians to raise and tilt their heads.
3) The appearance of the lungs as respiratory organs with atmospheric oxygen and the mechanism of air suction in them.
4) The appearance of the pulmonary pulmonary circulation and the second atrium.

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