you need a mining kit but you have to find it
Root Fossil Claw Fossil Helix Fossil Dome Fossil Old Amber Armor Fossil Skull Fossil Rare Bone
Yes the fossil is the skull fossil.
What's a skull fossil
Find a fossil underground. I did.
You can find Kabuto's fossil on the underground after obtaining the National Dex.
Ebay.
in sedimentary rock deposited by volcanoes
In Pokemon Diamond you take your fossil to Orenburg city. Go to the building above the Pokemon Center. Inside there is a man behind a desk. talk to him and he will take your fossil. walk out then back in. your fossil will have turned into a Pokemon. All Pokemon will be at level 20.
in mt moon
In the desert and in mirage tower.
go under ground to find them
Relic Castle in the desert