Quote Originally Posted by Urnamma
It implies that... it's newer. In fact, the reversion back to having a lot of cavalry with large shields during the middle Hellenistic period is a good counterweight to your sophistry here.
To be fair, many of the depictions of later Hellenistic cavalrymen with large round shields depict them wielding their spears underhand (whether that is a xuston or some other kind of spear).