Complex sentence: The hairstyle of the Terence portrait is close to the one favoured by emperors between the years 238 and 249, suggesting that models from which the codex was copied were made in the 3rd century.
Split into simpler sentences: The hairstyle of the Terence portrait is close to the one favoured by emperors between the years 238 and 249. It means that models from which the codex was copied were made in the 3rd century.