Vertebrate lungs probably evolved from simple outpocketings of the digestive tract of a freshwater fish.

Question

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The lungs of vertebrates are thought to have evolved from simple outpocketings of the digestive tract in early fish, which allowed them to extract oxygen from air, an adaptation that would have been advantageous in low-oxygen or variable oxygen environments, such as shallow or stagnant freshwater habitats.

Vertebrate Lungs Probably Evolved from Simple Outpocketings of the Digestive