Complex sentence: Among his many accomplishments, Thurmond set a regular season record for rebounds in a quarter with 18, and averaged 21.3 and 22.0 rebounds per game in the 1966--67 and 1967--68 seasons.
Split into simpler sentences: Among his many accomplishments, Thurmond set a regular season record for rebounds in a quarter with 18. He also averaged 21.3 and 22.0 rebounds per game in the 1966--67 and 1967--68 seasons.