Girvanella fossils from the Phanerozoic: Distribution, evolution and controlling factors

Girvanella is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of microbialites. Based on a detailed search in the literature of Girvanella fossils, we have compiled a global database of Girvanella fossils and revealed the evolution of Girvanella fossils throughout the Phanerozoic. Four species, Girvanella kasakiensis , Girvanella problematica , Girvanella wetheredii , and Girvanella staminea , are recognized and described. These data show that Girvanella fossils have well-defined temporal distribution during the Paleozoic Era, have a significant temporal gap in the Mesozoic Era, and have only been recorded sporadically in the Cenozoic Era. They were relatively abundant during the Cambrian Epoch 2–Early Ordovician, Late Ordovician, Late Devonian–Mississippian, and tended to lesser degrees during the Silurian–Early Devonian, Lopingian Epoch–Middle Jurassic, and Cretaceous–Present day. Furthermore, the evolution of the abundance and diversity of Girvanella fossils was fundamentally consistent and showed episodical declining during the Phanerozoic. To further explore these relationships, we thoroughly compared them with environmental factors such as seawater carbonate saturation state, Ca 2+ concentration, pH values, and atmospheric partial pressure of carbon dioxide ( p CO 2 ). This study indicates that seawater carbonate saturation state and Ca 2+ concentration are major controls on secular patterns of the abundance and diversity of Girvanella fossils, together with the secondary factors of pH values and p CO 2 . Considering the long history of Girvanella fossils, their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.