Build a smal open air base and fly with your argentavis and bring the megalo... in the base
Megaloceros

How ARK players tame and knock out the Megaloceros: what to feed it, what to knock it out with, and how to keep it safe.
They are are eating demophordon kibble and vegetables like potatos and carrots
Easy tame. Bola, tranq darts or arrows, then tame with crops or mejo berries if you don't have the kibble.
If you're lucky you'll find one at the coast in the snow biome. So it's near your raft.
Do pop hhahahhhahahahahahhahhahahahaahhahahahahahhaahahha