In this game , Bowser has kidnapped Princess Toadstool after she , Mario , and Luigi had a vacation in Dinosaur Land . Mario and Luigi must rescue her and seven Yoshi eggs from Bowser and his Koopalings . Mario , Luigi and Yoshi set out to save Princess Toadstool and Yoshi 's dinosaur friends , exploring Dinosaur Land for Bowser and his Koopalings .