 Two examples of the former kind are the "Judge Dredd" stories "Top Dog" and "Judgement Day", which both featured Johnny Alpha from the series "Strontium Dog" in a major role.Alpha lived over half a century in Dredd's future, and the crossover was accomplished by having Alpha time-travel back to Dredd's era.An example of the second kind is the "Judge Dredd" story "The Cursed Earth," which featured a dinosaur called Satanus who was described as the clone of the offspring of the female dinosaur which had appeared in most episodes of the earlier series "Flesh."