Legio II Parthica: the tombstones of Apamea

Legio II Parthica: one of the Roman legions. Its name indicates that it was recruited to fight against the Parthians, but it usually was Rome's strategical reserve, stationed in Italy.

On the courtyard of the museum of Apamea, there is a special collection of tombstones of Roman legionaries, almost all of them belonging to II Parthica. Most of these stones are of about equal size, and it looks as if some of them belong to a group burial. Is it possible that they belong to soldiers who were killed in action during the civil war between Macrinus and Heliogabalus (218)?

Other tombstones are from sites in the neighborhood and can be dated to the second and third centuries.