maybe written into the fossils mod, there’s an x% change of it containing useful DNA, and out of that useful DNA, only ~x% of the complete DNA, forcing you to find more fossils, or trade with other players. getting a complete DNA sequence finally allows you to revive the creature, which would be unique, so as to not populate the world with them. news of the discoveries would be at spawn, or scattered books, so other players can see the newly revived creature, or contribute some of their own DNA code they’ve discovered.