Complex sentence: New troop types such as the "Thureophoroi" and "Thorakitai" were developed, and they used the Celtic "Thureos" shield, of an oval shape that was similar to the shields of the Romans.
Split into simpler sentences: New troop types such as the "Thureophoroi" and the "Thorakitai" were developed. They used the Celtic "Thureos" shield, of an oval shape that was similar to the shields of the Romans.