1) Kill a wild Elderclaw and loot their seed

2) Plant seed in crop plot the way you would anything else (greenhouse effect, shovel, fertilizer, water)

3) It'll ask for cravings much like a dino carrying a rhynio baby. The ones I've seen so far are Black Pearls, Ammonite Bile, Sap, Biotoxin and Giant Bee Honey.

4) Once cravings are done it'll give you the option to harvest which turns it into a baby (babies seem to eat normal herbivore stuff to replenish food)