You have to take a fossil to Nacrene City Museum. The lady at the entrance will tell you that if you have any pokemon fossils, she can revive them for you. Give the fossils to her, leave the museum run around a bit, come back and she will give you what ever is in the fossil you got.
Dome Fossil - Kabuto
Helix Fossil - Omanyte
Old Amber - Aerodactyl
Claw Fossil - Anorith
Skull Fossil - Craniados
Shield Fossil - Shieldon
Cover Fossil - Tirtouga
Plume Fossil - Archen
Do you mean Archen? You can revive it in the museum from a fossil you get from a man in the Relic Castle. You can chose between this fossil and another one.
you need to revive it's fossil in Nacarene city's gym's museum's front desk
Revive the fossil from the scientist in Cinnabar Island.
As you enter the second gym the first lady on your right will be the one to revive your fossil.
You must revive its fossil.
If taken to cinnbar island's research lab you can revive the Pokemon inside the fossil which will be Kabuto.
you can revive it to get an anorith. the root fossil will give you lileep.
Anorith, a Rock/Bug type.
Mysterious fossil is not a Pokemon. Only Pokemon are listed on the Pokedex. You must revive the fossil in the Pewter City museum.
You have to let it evolve from a Anorith, which you have to revive from a Claw Fossil.
No you have to get the armor fossil and revive it then evolve it to a kabutops
Root Fossil Claw Fossil Helix Fossil Dome Fossil Old Amber Armor Fossil Skull Fossil Rare Bone