Why are lungfish considered important for understanding the evolution of land vertebrates?

Lungfish are significant to the study of vertebrate evolution because they exhibit physiological and anatomical traits that foreshadow the transition from water to land. While they are not direct ancestors of tetrapods, they are closely related to the sarcopterygian fishes from which land vertebrates emerged.12

Key evolutionary insights include:

• Circulatory Adaptations: Lungfish possess a partially divided heart and a specialized venous system that directs oxygenated blood from the lungs separately from deoxygenated blood. These modifications are strikingly similar to those found in [amphibians].1
• Respiratory Evolution: Their ability to breathe air using lungs provides a model for how early vertebrates may have adapted to poorly oxygenated aquatic environments, a precursor to terrestrial life.1
• Locomotion: Some modern lungfish, such as Protopterus annectens, utilize their fins to lift their bodies and perform walking or bounding gaits. This suggests that the fundamental motor behaviors associated with land-based movement may have originated in sarcopterygian ancestors before the formal emergence of limbs with digits.2