WHEN YOU BREAK OBSIDIAN WITH TO DOEDIC YOU ONLY GET STONE

DONT USE DOED!! Ankylo or Phoenix is the best by far, this is from personal experience. Doed gets you only stone from MOST the obsidian around, on some maps there is another kind which has metal too, that is the ONLY kind a doed can even harvest at all.
PHOENIX IS BADASS!! mine was 37 b4 tame, and now has replaced my quetz cause it has a weight over 1200, and it can harvest all the same stuff as an Ankylo, not as good, but not much worse tbh.

On Rag use a dunk in the obsidian trench north of the volcano underwater. Absolutely insane amounts of metal and Obsidian

There are two type of obsidian rocks. Search the one who also drop metal. That's the kind that you should break if you're using a doedicurus. If you break the type that doesn't also drop metal the doedicurus will only harvest stone.

High melee doed hands down the best just keep throwing out the stone and metal so to not be over weight so fast

What I have found to be the best is using magmasaurs. Getting about 150 per rock instead of 30 to 60 with anky. (On official)

You may think you get obsidian that you don’t get it only rocks and metal it gives