A Comparative Study of Three Types of Dasycladalean Algae (Dasyporella, Vermiporella, Catenuporella gigantia) Fossils from the Late Ordovician Beiguoshan Formation in Ordos

To explore the morphological characteristics and palaeoecological significance of Late Ordovician calcified dasycladalean algae, this study conducts a comparative analysis of Dasyporella, Vermiporella and Catenuporella gigantia based on field section data and thin-section rock samples collected from the southwestern margin of the Ordos Basin and Zhuzhai area in Yushan, northeastern Jiangxi. The results show that obvious differences exist among the three dasycladalean algae in thallus morphology, central cavity, calcified wall and living environment. Among them, Catenuporella gigantia is mainly distributed in high-energy reef facies environments; Vermiporella has a wide adaptive range; Dasyporella is mostly found in bank facies limestone. Different dasycladalean algal assemblages can reflect variations in hydrodynamic conditions and sedimentary environments, providing a basis for sedimentary facies identification and palaeoecological reconstruction of the Late Ordovician.