This the first ancient coin I bought. Seller looks reputable. What do you think? I got it off Vcoins. Greece, Sicily, Syracuse, 275-215 BC, AE 22, BMC 2.603, AVF Head of Poseidon, left wearing tainia/Rev. Ornamented Trident-head between 2 dolphins
Looks like you've got your reverse upside down. Here's mine: Hieron II, 275-215 BC Æ19, 6.3g, 12h; Syracuse mint. Obv.: Diademed head of Poseidon left. Rev.: Ornamented trident head, dolphin downward flanking on each side, ΙΕΡΩ−ΝΟΣ horizontal across field divided by shaft, uncertain control symbols.
One of my favorite types! Hieron II, Syracuse, 275-215 BC O: Poseidon, R: Trident between dolphins, ΙΕΡΩ−ΝΟΣ below, 20 mm, 6.6g, Calciati-197
When I flip it over from obverse to reverse, the top of Poseidon’s head matches with the points of the trident facing up.
In ancient coins, the alignment with the reverse often isn't aligned with the obverse. Certain empires, locations, times had documented trends in their alignment that can even help document their period of time and who struck them, be them 180 degrees, 0 degrees or any degrees. There was no official alignment standard in antiquity. Why it is believed to have the trident facing upwards is based on the text that usually appears below in the fields around the shaft, and the direction of that text dictates it was facing upwards (see text on above examples).