Best way to counter them. Tame a high level procoptodon. Only level health and stamina. Take it to an obelisk, then access the obeliskand pick to save the procoptodon and then go scorched earth and jump into a wyvern trench and get the egg.In the island tame a bronto, then transfer the bronto , take it to the trench, lure the wyverns to a turret box use the bronto for cover. Use the wyvern against rhynios