Complex sentence: Theodor Seuss Geisel (March 2,1904--September 24,1991) was an American writer, poet, and cartoonist most widely known for his children's books written and illustrated as Dr. Seuss.
Split into simpler sentences: Theodor Seuss Geisel (March 2,1904--September 24,1991) was an American writer, poet, and cartoonist. He was most widely known for his children's books written and illustrated as Dr. Seuss.