Before revision: Extinct isotopes of superheavy elements are isotopes of superheavy elements whose half-lives were too short to have lasted through the formation of the Solar System, and because they are not replenished by natural processes, can nowadays only be found as their daughters trapped within sediment and meteorite samples dating billions of years ago.
After revision: Extinct isotopes of superheavy elements are isotopes of superheavy elements whose half-lives were too short to have lasted through the formation of the Solar System, and because they are not replenished by natural processes, can nowadays only be found as their decay products (from alpha decay, cluster decay or spontaneous fission) trapped within sediment and meteorite samples dating billions of years ago.