How do you get the claw fossil on Pokemon emerald?

You can't get the Claw Fossil in Pokemon Emerald. The Claw Fossil is exclusive to Pokemon Ruby and Sapphire.

In Pokemon Emerald, you can find the following fossils:

* Old Amber: Found in the Shoal Cave and can be revived into Aerodactyl.

* Root Fossil: Found in the Shoal Cave and can be revived into Lileep.

* Skull Fossil: Found in the Shoal Cave and can be revived into Anorith.

To get these fossils, you'll need to explore the Shoal Cave and find them within the caves. Be sure to bring a pickaxe with you, as you'll need it to break the rocks containing the fossils.