Explore the fascinating early evolution of fish and their relatives in this comprehensive lecture. Delve into the first great divide, starting from the bottom and progressing through chordates to more "fish-like" groups. Examine the cephalochordata and their larval forms, before diving into true fish. Investigate potential early fish forms like Pikaia and Haikouichthys, and learn about modern cyclostomata. Uncover the enigmatic conodonts and explore the diversity of pteraspidomorphs, including thelodonts, aspids, and osteostracans. Gain a deep understanding of the rich history and diverse lineages that shaped the evolution of fishes.