A surprise fossil find around one of my usual trails. This species is known from the Del Rio Formation (Middle Cretaceous: Cenomanian stage).

Several university collections still erroneously denote this as "Exogyra arietina" despite Exogyra s.l. being split into a few genera in 1971 by Stenzel. I recall being rather perturbed in undergrad over this species and those of Amphidonte being labeled as the same genus as Exogyra ponderosa.