Simplify the following text for a Grade 11 native English-speaking person.
Original: New evidence based on accurate optically stimulated luminescence and uranium-thorium dating of megafaunal remains suggests that humans were the ultimate cause of the extinction of megafauna in Australia .
Simplified: Scientists have got new evidence , based on new and better ways of finding dates , using optically stimulated luminescence and Uranium-thorium dating of megafaunal bones . This suggests that humans were the main cause of the extinction of megafauna in Australia .