Complex sentence: Petra Kelly was one of the founders in 1979 of "Die Grünen", the German Green Party, serving from 1983 to 1990 as a member of the Bundestag (West German Parliament).
Split into simpler sentences: Petra Kelly was one of the founders in 1979 of "Die Grünen", the German Green Party. Between 1983 and 1990, she was a member of the Bundestag (West German Parliament).