What evidence places fish as the first vertebrates?

Fish are considered the first vertebrates based on fossil evidence and evolutionary Biology. The earliest known vertebrate fossils, such as those from the Cambrian period, show primitive fish-like creatures with key vertebrate features, including a notochord and early forms of vertebrae. Additionally, molecular studies suggest that the lineage leading to modern vertebrates diverged from other chordates around the same time that these early fish appeared. These findings collectively support the idea that fish were the first vertebrates to emerge in the evolutionary history of life.