Complex sentence: Macrinus, upon learning of his son's death, tried to escape captivity, but he injured himself in the unsuccessful attempt and was afterward executed in Cappadocia; his head was sent to Elegabalus.
Split into simpler sentences: Macrinus, upon learning of his son's death, tried to escape captivity, injuring himself in the process. His attempt at escape failed, and Macrinus was executed in Cappadocia and his head was sent to Elegabalus.