Extinct or Not?

One group of cryptids are animals that are thought to be extinct but reappear. The proper term for that group is Lazarus Taxon. Some of these cryptids possibly include megalodons, thylacines, and moas. I learned this term from a TV show called "Megalodon, the Monster Shark Lives."  Lazarus taxon refers to Lazarus in the bible who Jesus raised from the dead, and a taxon is any unit used in the science of biological classification, or taxonomy.