You can get other fossils when you defeat the Elite Four and the Champion and receive the National Pokedex in Pokemon Diamond.
Armour,Skull,Helix,Dome,Old Amber and Root Fossils.
You go underground and just search. Skull fossils appear at random, but they aren't all that rare. You just have to search. Also, Cranidos Skull fossils can only be found in Pokemon diamond, and Sheildon Armor Fossils can only be found in Pokemon pearl.
A place you where give fossils for Pokemon like Cranidos for the skull fossil.
Skull fossils. If you want proof, I honestly think that I have 15 cranidos on diamond.
I'm not sure what fossils you're looking for, but you can get Helix ,Dome,Amber,Armour and Skull Fossils. In Diamond, you can get a Skull Fossil. In Pearl you can get a Armour Fossil. All other fossils can be gotten after both games.
saltwater
In the underground.
In Pokemon Diamond you can find a Skull Fossil (different guy) i think he means what fossils do you find. here are the ones i know of, just in case; skull, shield, root, old amber, claw, that water thingy that is an omyanite and maybe more.
I'm not sure exactly if you can get it in diamond..... But if you can, you have to dig it up underground
skull fossil and amour fossil
Of course. You can get them in Diamond, Pearl, Platinum. Go underground using Explorers Kit found in Eterna City (digger man gives you it his house is next to Pokemon Center) then, if your trainer's ID is even, you find ONLY armor fossils. If it's odd, you find ONLY Skull Fossils. once you get the National Pokedex, though, they are reversed. Odd, Armor fossils, Even, Skull Fossils.
skull=Cranidos(diamond only) armour=Sheildon(pearl only) dome=kabuto helix=Omanyte claw=anorith root=lilleep old amber=aerodactyl