1. Jaws: The development of jaws allowed fish to become active predators and diversify their diets. Before jaws, early fish relied on filter feeding or sucking in food. Jaws allowed them to grasp and tear prey, opening up new food sources and niches.
2. Paired fins: Paired fins, specifically pectoral and pelvic fins, provided greater maneuverability and control over movement. This allowed fish to navigate complex environments, explore new habitats, and become more efficient hunters. Paired fins also laid the foundation for the development of limbs in terrestrial vertebrates.
These two characteristics played a crucial role in the diversification and success of fish, ultimately leading to the evolution of amphibians and other land-dwelling vertebrates.