In amongst the simplified characters, there are a few ancient forms, such as 无 where traditional generally uses 無. Now, 无 appears in Shuowen as 奇字 an odd form of 無, but 無 appears in the bronze inscriptions, and 无 does not. Actually, in the oracle inscriptions they used 亡（兦), which you still see in some texts, such as the Book of the Han.
What I think is too bad is that they missed the chance to resurrect a lot old characters that are simpler to write, 亼 for 集, or for 杂/雜 they could have used 帀 (~… it’s not on the computer, the right side of 師.~ updated, thanks to Tim Tran)
But a simplified character that is older than a traditional character? I can’t think of any, you’d have to give me an example.