I believe it should be at the ruin of alph but may require some time to get because of it's rarity. Pewter city is where you can revive it.
Im pretty sure you dont catch aerodactyl in heartgold but I think you can get him as a fossil, if you do, talk to the guy in the pewter city mueseum and he will turn it into aerodactyl for you.
Get a old amber and take it to a guy in the museum in Petwer City,
omanyte and anorith and aerodactyl
You can not get an Armor Fossil in HeartGold.
You cannot get a Skull Fossil (Cranidos) in Pokemon HeartGold.
In Pokemon LeafGreen, the Dome Fossil can be revived into Kabuto, and the Helix Fossil can be revived into Omanyte.
Yes you can. Use HM Rock Smash in the following places; Ruins of Alph: Helix fossil (Omanyte) and Old Amber (Aerodactyl) Cliff Cave: Claw fossil (Anorith)
Neither the Helix Fossil nor the Dome Fossil will become an aerodactyl. In order to obtain an aerodactyl you must revive a pokemon from the Old Amber item which can be obtained in the Pewter City Museum.
Aerodactyl
If you're talking about an in-game trade, then no.
Answer:If you mean in Pokemon, there is no other fossil like it, and it becomes an aerodactyl.
Aerodactyl FOSSILS can be found in the ruins of alph, among other places. The fossil is called OLD AMBER to REVIVE the fossil, you have to beat the elite 4 and get to Pewter City in KANTO. Hope that helped!:)