As @TeaLovingDave will know, the signage here listed both P. megacephalus and Scinax sp. so both will be possibilities. I also remember our initial thoughts being that these were two different species perhaps.
@ThylacineAlive Complicating factor there..... the megacephalus were in a different tank altogether separated from this one by about four tanks.
This tank was signposted for Scinax sp. , Sylvirana cubitalis and Osteopilus septentrionalis, and our uncertainty was whether these particular frogs were multiple species of Scinax, or both Scinax sp and the Osteopilus.
@TeaLovingDave The way I have the scientific names written down in my notes has megacephalus right next to the rest of those species. Hazards of not taking more detailed, enclosure by enclosure notes