An introductory report on the biodiversity of Middle Jurassic Phoenicopsis (Czekanowskiales) from the Ordos Basin, China

Although the genus Phoenicopsis is the most common member of Czekanowskiales and is considered an indicative representative of the Middle Jurassic Coniopteris-Phoenicopsis assemblage in northern China, little was known about its taxonomy and biodiversity based upon the leaf cuticular structure. In this paper, three subgenera of the genus Phoenicopsis from the Middle Jurassic, Yan'an Formation of the Ordos Basin, China, Phoenicopsis (subg. Phoenicopsis (Heer) Samylina, P. (subg. Windwardia) (Florin) Samylina and P. (subg. Culgoweria) (Florin) Samylina are identified based upon the leaf epidermal features for the first time. This discovery demonstrates that Phoenicopsis was quite diverse during the Middle Jurassic in northern China. Its biodiversity is significant for further understanding Middle Jurassic paleophytogeography and paleoclimatology of northern China. The current findings show that the three Phoenicopsis subgenera coexisted and flourished in the mixed zone (ecotone) between the Indo-Sinian Floristic Region and the Siberian Floristic Region as seasonal deciduous plants (trees or shrubs) during the Middle Jurassic. They were important elements in the Middle Jurassic deciduous gymnospermous forest community in warm temperate regions with seasonal temperature and precipitation variations. They are interpreted as growing on the hillsides and sloping fields along meandering streams, lakes and swamps in a vast sedimentary basin in a wet and warm environment.