Complex sentence: Sculptural portrait heads from classical antiquity are sometimes displayed as busts, but these are often fragments from full-body statues, or were originally created to be inserted into a preexisting body; these portrait heads are not included in this article.
Split into simpler sentences: Sculptural portrait heads from classical antiquity are sometimes displayed as busts. However, these are often fragments from full-body statues, or were originally created to be inserted into a pre-existing body; these portrait heads are not included in this article.