Use the Explorer kit. Dig in the walls and you'll probobly find one. Once you beat the Elite Four and the Champion you have a much greater chance of finding a fossil. Crainidos are harder to find then Shelidos, I've found 5 Shelidos fossils and only one Crainidos so you'll have to have alot of patience.
go underground get a skull fossil and get it restored
you can not find a wild rampardos in platinum you have to catch a cranidos by finding a skull fossil underground and then evolve cranidos at lv. 30 hope that helps =)
To find Cranidos on Platinum, you have to dig underground for a skull fossil. Then go to Orburgh City and go to the museum. Talk to the Scientist and he will revive it into a level 20 Cranidos! -Hope this helps! :)
Underground
Cranidos
You need to go underground and find a skull fossil and go the oreburgh city museum and they will give you a cranidos
Alright actually you can get Cranidos in pearl. All you need is the national pokedex. Go back to the underground until you find the fossil but you do need the national pokedex to find it.
You can get all the fossils underground, except for shieldon or cranidos. You find shieldon if your ID is even and Cranidos is your ID is odd.
You can't catch it; you have to go underground and find a Skull Fossil. Then go to the museum in Oreburgh City and talk to the Scientist guy. Ask him to revive it, and then he'll give you a Cranidos at Level 20.
To get Cranidos on Pokémon Diamond DS go underground and dig up a skull fossil. You then take it to the Oreburgh museum and revive the skull into Cranidos.
Go underground and dig up a skull fossil,then go to the mining museum and the person behind the counter when you go straight will give it to you.
you need the skull fossil whic you can get underground