EXTICTION OF QUATERNARY MAMMALIAN HABITATS OF MEGAFAUNA IN SABARAGAMU BASIN - SRI LANKA
1#Aravinda Ravibhanu Sumanarathna 2Jinadasa Katupotha 3Kamal Abeywardana
1,3 South Asian Astrobiology & Palaeobiology Research Unit of Eco Astronomy Sri Lanka.
2 Department of Geography: University of Jayawardenepura
1Faculty of Enviroment & Natural Science University of Southampton –United Kingdom
The Quaternary includes two geologic epochs: the Pleistocene and the Holocene. Both epochs divided to faunal stages and human cultural phases based on climate and sea level cycles for the past three million years. Quaternary ice age begins roughly 2.58 Ma with cool and dry climate conditions. Australopithecines and many of the extinct genera of mammalian mega fauna appeared in this time. Thus, the Quaternary period show the extinctions of numerous predominantly larger, especially mammalian mega faunal species, many of them lived during the transition from the Pleistocene to the Holocene epoch. The debate on the demise of the mammalian megafauna is often characterized by two highly polarized points of view: (1) climate-induced extinction; and (2) human-induced extinction. In Pleistocene period most parts of the Northern Hemisphere were covered with glaciers creating a cold climate. Due to this glacial formation the main sea level was much lower than today. The low sea level facilitated the connection of Sri Lanka with the Indian mainland with a land bridge. Therefore a number of mega and micro fauna was able to cross to Sri Lanka from India. The last land bridge was emerged around 7500 yr BP. In Pleistocene era Sri Lanka experienced heavy rainfall and covered with rain forest. These heavy showers in the Sabaragamu basin provide habitats for a number of Marsh loving mammals and other animals. However at the end of Pleistocene the climate changes resulted in the extinction of number of a animals. Pleistocene fauna in Sri Lanka is known as Rathnapura Fauna. These fossils were found in alluvial deposits of Sabaragamu basins.
Key Words: Quaternary mammalian, Sabaragamu Basin, Ratnapura fauna, Extinction, Gem gravels.