Dododex
ARK: Survival Evolved & Ascended Companion
Tips & Strategies

I found that pairing this fella with a pteranodon is very useful. You can pick it up and fly into the water, which dismounts you and drops it. You can immediately get on the diplocaulus once in the water, and when you want to leave the water you can jump back on the pteranodon and pick it up.
More Diplocaulus Utility Tips
These guys are the kings of trilobite hunting. Not only do they deal additional damage to them, they're great at collecting chitin, oil, and pearls. Other perks: they don't need a saddle to be ridden while in the water, they provide you with oxygen underwater, and are faster than just about anything while swimming. Super underrated mounts imo.
Please listen to me! I haven't had these guys for long, but I noticed their healing was very low, about 0.1, while on land. When I went into the water with it so it could swim, the healing went up to about 1.2 per second. But the biggest thing is, I force fed it meat to heal, like with all carnivores. If you do this in the water, it heals hundreds with just a few pieces! I am going out to the seas in a bit. Knowing this healing factor will help a lot!