Complex sentence: Fermilab's first director, Robert Wilson brought five American Bison to the site in 1967, a bull and four cows, and an additional 21 were provided by the Illinois Department of Conservation.
Split into simpler sentences: Fermilab's first director, Robert Wilson brought five American Bison, a bull and four cows in 1967. They were joined by an additional 21 provided by the Illinois Department of Conservation.