Complex sentence: Dorothy Fields (July 15,1905--March 28,1974) was a U.S. librettist and lyricist who wrote well over 400 songs for Broadway musicals and films.
Split into simpler sentences: Dorothy Fields (July 15,1905--March 28,1974) was a U.S. librettist and lyricist. She wrote over 400 songs for Broadway musicals and films.