The size of Imperial shields?

[Nathan Ross]

there aren't many that I know of

Twenty-four whole or fragmentary shield boards were found at Dura Europos; of these, the complete rectangular scutum found in the ruins of Tower 19 measures 1.06 metres by 0.86 metres, and I believe this is the size usually adopted for reconstructions. A number of oval shields from the same site are of comparable size: 1.18x0.95 for the 'Homeric' shield, 1.17x0.97 for the 'Amazons' shield, 1.18x0.94 for the 'Warrior God' shield.

The 'republican'/Hellenistic oval scutum from Fayum in Egypt measures 1.28x0.6m, the native British oval shield from Doncaster is 1.25x0.6m, and leather imperial-era shield covers found at Vindonissa are of similar size to the Dura and Fayum shields.