When we think of American cinema in the 1970s — that heralded period known as the New Hollywood, when studios were taking risks and adventurous young filmmakers were breaking all the rules — different actors spring to mind as emblems of the era. Jack Nicholson. Al Pacino . Gene Hackman. Warren Beatty . One name that may be less obvious but should be on that list: Diane Keaton . Later in her career, the beloved Oscar winner, who died Saturday at the age of 79, delighted audiences in comedy hits