Fantastic mount. Don't engage in a final with the Argentavis though, it's guaranteed to lose it. Try to paint it white and claim it was always white. Best taming method is getting it close to some tiny islands, from there, engage.
I was out busy collecting berries for a trike I was taming. Successfully tamed the trike, so proud! Then I heard an eagle sound. Now me and my trike live inside this feather brains belly. Smells grim. Oh look I found my dodo!