On this blog I sometimes talk about the UD Boundary. This is a reference to the geological event that wiped out the dinosaurs, generally thought to be a massive asteroid impact. The fall out from the huge impact left a small layer of iridium across the planet's surface and this is visible in geological strata everywhere. This is known as the KT boundary. It's link to the extinction event is surmised because no dinosuar fossils appear in undisturbed rocks above the KT Boundary.
The jury is out on what caused the rapid extinction of the old cards. The blame is often placed on the Upper Deck meteorite, which landed in 1989 and was hugely popular. But the Upper Deck meteorite was not the first impact on the card world. Score were running pictures on the backs of cards prior to Upper Deck's arrival. However, Upper Deck arguably had more of an impact than Score, so UD Boundary works better as a descriptor.