Abstract: Scleractinia, one of the most important builders of modern reefs, are important today and in the geologic past. As one of the most important problems in the coral study, the origin of Scleractinia has remained shrouded in controvery: There is no agreement on whether Scleractinia originated from Paleozoic Rugosa, or a kind of scleractiniamorphs, or a group of anemones. The traditional way based on the morphological characters of extant Scleractinia and their fossil record and the molecular systematics are two means used to study the origin of Scleractinia. The authors used the way of molecular biology to sequence corals’18S rDNA, and reconstructed Class Anthozoan’s phylogenetic trees. The authors conducted comparative study of morphology and molecular systematics, and tried to solve these conflicting problems about the origin of Scleractinia.

Key words: origin of Scleractinia, morphology, molecular systematics