In Tampa Bay, marine biologist, Linda Holland, studies amphioxus, finding this simple animal with its novochord, clearly linked to human evolution. Her studies pinpoint the evolution of body form in amphioxus, chicks, and other animals with a backbone. She also explains how the duplication of genes enabled larger animals to evolve. The second segment recalls the evolutionary period dominated by fishes and the emergence of tetrapods on land. Paleontologist Jenny Clack, recalls how she discovered the transitional form. The segment also studies monitor lizards as examples of the development of tetrapods. The third segment relates amphioxus to the evolution of dinosaurs. In Montana, Kristi Curry-Rogers, a palentologist, explains why she believes dinosaurs grew large very quickly. The fourth segment explains how mammals evolved after the extinction of the dinosaurs. For Teacher's Guides go to: https://drive.google.com/folderview?id=0B9ZT7PYcIjLffk5QOEpyUGs2NnQ3cjRETGlnZHB3RjN3VkRrSC1wZWxUQ3pwWGFxRV9lYlU&usp=sharin