Unlike unbreedables and breedables these monsters are replaced by following and no longer breedable and any way to get it. Until September 2016 when they were all re-added into the game as part of the Secret Vintage Collection. Rumour has it that there is a 1% Chance to breed these Monsters with two Legendary Monsters.
Firesaur replaced Firelion
Treezard replaced Panda
Mersnake replaced Turtle
Greenasaur or Pandaken replaced Firanda
Received a turtle as a Monday prize on March 30 2014