Bullfrog tadpoles or not?

Tadpoles can be tough to identify and I do not often have the patience to count tooth rows or such. I netted some tadpoles yesterday at one of our ponds where I know that both bullfrogs and green frogs are present. I only know for certain that bullfrogs have bred here. Many of the older tadpoles (see photos) show distinct black spots. If I recall correctly, such punctate, clearly defined spots are characteristic of bullfrog tadpoles, not green frogs.Does anyone else have similar or different experiences?

Bill Dunson, Galax