Complex sentence: Russell's long and curly hair was one of her character's defining characteristics, and a drastic hairstyle change at the beginning of the show's second season was considered to be the cause of a significant drop in the show's television ratings.
Split into simpler sentences: Russell's long and curly hair was one of her character's defining characteristics. A drastic hairstyle change at the beginning of the show's second season was thought to cause a significant drop in the show's television ratings.