Complex sentence: At Santa Anita Park the four-year-old horse won the Santa Anita Maturity and at Hollywood Park Racetrack won the Sunset Handicap, Argonaut Handicap, and the Inglewood Handicap.
Split into simpler sentences: At Santa Anita Park, the four-year-old horse won the Santa Anita Maturity. At Hollywood Park Racetrack, he won the Sunset Handicap, Argonaut Handicap, and Inglewood Handicap.