Cladiastics used to be based on phyiscal characteristics, but now genetic characteristics. And it's actually pretty easy to tell the age of a gene reliably by looking at its radiation.
Anyway, you continue to misunderstand how evolution is supported. And until you actually take a comparative anatomy class, you'll continue to not understand. Things aren't considered ancestors simply because their older. It's because of how similarities and differences are. Even if people get it wrong at times, the method s still strong. Even if a time-warped raccoon fossil were discovered and labeled a red panda ancestor, that wouldn't prevent the fact that the red panda ancestor likely looked like both a racoon and red panda.