One of the smallest of the papyri in the files of cohors XX Palmyrenorum stationed at Dura-Europos in Syria Coele appears to be one of the most interesting. It is P. Dura 81, which is dated, on similarity of style to another document, to c. A.D. 251:

On the fourth line J. F. Gilliam the editor comments: ‘Following -athon it appears that o was first written and then corrected to i. Possibly these letters are part of a name, perhaps the nomen of Marcellus. Mathoni would be possible, though surprising.’
However, the reading is almost certainly correct as it stands. A Marcus Aurelius Atho Marcellus is attested by two inscriptions as being procurator Mauretaniae Caesariensis at some time between A.D. 246 and 249. I suggest that he is the same person as the man mentioned at Dura for four reasons: Atho is the only example of this nomen to be found in PIR2; the combination with Marcellus; they are both procurators of high rank; they are contemporary.