Where have our Eagles gone?

[Titvs Statilivs Castvs]

I'm sorry, but afaik, that's not abstract art. It's figurative. It might be not quite exactly representing the real things, but that doesn't make it abstract art.
If we look at the statues of the soldiers in the one of the pictures you showed, they are not represented equally to the reality, for example their spears. Neither is the eagle on the coin.