You find them underground. If you want to go underground, get the explorer kit from the underground man in Eterna City, in a house next door to the Pokemon Center.
Then you have to click on the touchscreen once you get underground and if you see a sparkling yellow diamond, then go over there and click on it with a the button 'A'
Find a fossil underground. I did.
You cannot get Cranidos in Pokemon Pearl unless you trade to get the Skull Fossil from a friend. You can only find a Skull Fossil in Diamond.
at the oreburgh mining museum:)
At the beginning of the game before getting the national pokedex you can get: Skull Fossil - Cranidos *Exclusive to Pokemon diamond Armor Fossil - Sheildon *Exclusive to Pokemon pearl After receiving the national dex you can also find: Helix Fossil - Omanyte Dome Fossil - Kabuto Old Amber - Aerodactyl Claw Fossil - Anorith Root Fossil - Lileep
The same way you get a skull fossil on diamond, dig in the underground till you find one.
There is armour fossil in Pokemon pearl, it is a fossil that has a shieldon in it, or you could trade with someone from diamond for a cranidos.
Helix fossil
Its a sheildon fossil
pearl is not a fossil, you sell it at pokemon marts for lots of CHA CHING
diamond- skull fossil- cranidos-rampardos pearl-armor fossil- sheldon-bastiodon
in the underground.
Underground