Where can you get the Armor Fossil in Platinum?
By mining in the Sinnoh Underground.
The Armor Fossil can only be obtained in this location if your Trainer ID Number ends with an even number (0, 2, 4, 6, 8). If it ends in an odd number (1, 3, 5, 7, 9) you may only find the Skull Fossil.
http://bulbapedia.bulbagarden.net/wiki/Skull_and_Armor_Fossils
