This coin is an unattested variant of a known Corinthian reverse type without shield (see Comparanda). It appears as example 3 in RPC on-line: https://rpc.ashmus.ox.ac.uk/coin/454128
Laureate and draped bust of emperor to right; within dotted border
Obverse Inscription
[M AVR] ANTO-[NI]N[VS AVG P M]
Reverse Description
[Helmeted] Athena in peplos standing to left, holding spear in upraised left hand and Nike (traces) in outstretched right hand; shield resting upright against left leg and owl on ground next to right leg; all within dotted border