Final answer:
The first vertebrates with jaws were the jawed fishes, or Gnathostomes. They were derived from the gill arches of jawless fishes. Jawed fishes were highly successful and diversified into various species, making them the most diverse group of vertebrates.
Step-by-step explanation:
The first vertebrates with jaws were the jawed fishes, also known as Gnathostomes. Jaws were a significant development in the evolution of vertebrates, allowing them to grasp and tear their food. They were derived from the first pair of gill arches supporting the gills of jawless fishes.
The jawed fishes were highly successful in their evolution. Over time, they diversified into various species, including the modern fishes we see today. Jawed fishes are the most diverse group of vertebrates, consisting of approximately 31,000 species.