Complex sentence: He was by a Leading sire in North America, Palace Music (by the The Minstrel), his dam Solar Slew, was by the 1977 Triple Crown winner, Seattle Slew.
Split into simpler sentences: He was by a Leading sire in North America, Palace Music (by the The Minstrel). His dam, Solar Slew, was by the 1977 Triple Crown winner, Seattle Slew.