Late Repubican Scutum designs

[Kaxezoa]

Hi all,

This is a subject that has eluded me for a while now and that regards plausible and accurate designs for shield decorations, particularly for the Gallic and civil wars of the late republic. There's a mountain of depictions online for Caesarian legions having winged and thunderbolt designs but no actual evidence for it that I can see in reliefs from the time period (aside from the single shield on Augustan era relief for the battle of actium) - attached is roughly what I'm concerned with.
           

My question I guess is there any evidence for this, if not why has this design become so prominent, featuring heavily on art produced in books and on Ancient Warfare's own issues. I've wanted to recreate this design on res bellica's republican scutum but this intrigue has held me up,

[Robert Vermaat]

is there any evidence for this

Hardly any. There is artwork, carvings, that sort of thing, but it doesn't tell us much about unit shield designs and any changes therein. And not for the colours apart from general descriptions.