The Early Cambrian Haikouichthys and Haikouella have been claimed to be related to contribute in an important way to our understanding of vertebrate origin, but there have been heated debates about how exactly they are to be interpreted. New discoveries of numerous speci-mens of Haikouichthys not only confirm the identity of pre-viously described structures such as the dorsal and the ven-tral fins, and chevron-shaped myomeres, but also reveal many new important characteristics, including sensory or-gans of the head (e.g. large eyes), and a prominent notochord with differentiated vertebral elements. This 揻irst fish?ap-pears, however, to retain primitive reproductive features of acraniates, suggesting that it is a stem-group craniates. A new order (Myllokunmingiida) and a new family (Myllo-kunmingiidae) are erected, and a new species, Zhongjianich-thys rostratus (gen. et sp. nov.), is described herein. Over 1400 newly-discovered specimens of Haikouella provide a wealth of anatomical information on this organism. It differs from chordates in many organs and organ systems, including the skin, muscles, respiratory, circulatory and nervous sys-tems. In contrast, its body-design resembles that of vetuli-colians, and the presence of a 搕ransitional?nervous system with both dorsal and ventral nerve cords suggests an affinity with living hemichordates. On the basis of these and other recent findings of fossil deuterostomes, a five-step hypothesis for vertebrate origin is proposed, intended to bridge the long- standing gap between protostomes and vertebrates. Four of the five steps accord with established ideas current in modern evolutionary zoology. Evidence for the first step is obtainable only from fossils, and specifically from fossils found from South China, hence the crucial importance of S. China sites for our understanding of early vertebrate origins and evolution. Accordingly, South China is suggested as the oldest-known birthplace of the whole vertebrates. The Early Cambrian Haikouichthys and Haikouella have been claimed to be related to contribute in an important way to our understanding of vertebrate origin, but there have been heated debates about how exactly to be be interpreted. New discoveries of numerous speci-mens of Haikouichthys not only confirm the identity of pre-viously described structures such as the dorsal and the ven-tral fins, and chevron-shaped myomeres, but also reveal many new important characteristics, including sensory or-gans of the head (eg large eyes), and a not irst fish ap ap-pears, however, to retain primitive reproductive features of acraniates, suggesting that it is a stem-group craniates. A new order (Myllokunmingiida) and a new family (Myllo- Over 1400 newly-discovered specimens of Haikouella provide a wealth of anatomical in It’s different from chordates in many organs and organ systems, including the skin, muscles, respiratory, circulatory and nervous sys- tems. In contrast, its body-design resembles that of vetuli-colians, and the presence of a The ransitional? Nervous system with both dorsal and ventral nerve cords suggests an affinity with living hemichordates. On the basis of these and other recent findings of fossil deuterostomes, a five-step hypothesis for vertebrate origin is proposed, intended to bridge the long- standing gap between protostomes and vertebrates. Four of the five steps accord with established ideas current in modern evolutionary zoology. Evidence for the first step is obtainable only from fossils, and specifically from fossils found from South China, hence the crucial importance of S. China sites for our understanding of early vertebrate origins and evolution.