when were the Danum shields used??

[Peroni]

Hmmm. A good size for a deep curved scutum?

Yes it is, I agree, but the flange of the shield boss is flat Jim. Hence my agreeing with the vertical grip. If it were deeply curved, you would be more likely to see a square or hexagonally flanged umbo. not a circular one. As Martinus said, trying to put a curve into a narrow-flanged circular umbo is very difficult to achieve.