A preliminary report on the freshwater molluscan fossils from Myanmar

Abstract

Three named species and nine indeterminate species of freshwater molluscan fossils are found from the Eocene, Mio-Pleistocene, and Holocene of central Myanmar. The Eocene fossils are found from the Pondaung Formation and consist of an indeterminate viviparid gastropod, indicating a shallow-water environment. The Mio-Pleistocene fossils were found from the Irrawaddy Beds and consists of Melanoides sp. indet., Brotia costula, Indonaia? sp. indet., Radiatula sp. cf. Radiatula lima, Lamellidens sp. indet., Parreysia favidens, and P. pernodulosa. The molluscan fauna of the Irrawaddy Beds is characterized by occurrence of comparative species in Myanmar and in South Asia, indicating that a similar water system with present one in that time. The Holocene fossils were found from the Buddaw Zinaw Cave deposit and consist of Margarya sp. and Brotia costula. Among the Holocene fossils, Margarya is a representative genus of the recent freshwater molluscan fauna of Yunnan (southern China), indicating that a water system extended between Yunnan and central Myanmar in that time.