Fig. 13

Comparisons between calcareous algae and cyanobacteria. a-b Dasycladales, whose calcareous skeletons were composed of granular calcite, from the Upper Ordovician of Shijiezigou area in the Ordos Basin, Ningxia, Northwest China; c-d Gymnocodiacean Permocalculus sp., a common Permian Codiaceae green alga of the Bryopsidales, with a calcareous skeleton composed of granular calcite, from the Middle Permian Lengwu Formation of the Lengwu section in Tonglu County, Zhejiang Province, East China; e Girvanella, a representative of the filamentous calcified cyanobacteria, possesses unbranched filaments with thin micritic walls, from the Middle Ordovician of the Qianlishan section in the northwestern Ordos Basin; f A mushroom-like skeleton of Pseudosolenopora filiformis (Nicholson 1888), composed of calcified cell trichomes in radiate arrangement, with calcified cell walls composed of micrites, from the Upper Ordovician of Well 822 in the Tarim Basin, Xinjiang, Northwest China (Yang et al. 2015)