Take it to upper south cave and murder the ever living fuck out of every single piranha that you can find. It regenerates health just by killing the fishes, and while the piranhas are too small to be affected by the stun effect, the spin attack still has a full 360 AoE. The Baryonyx will effectively cancel out ANY damage dealt by those little pests!
Baryonyx are quick like Allosaurus and do just as much damage (but don't get a pack bonus). They don't use oxygen for swimming and can sprint in the water. Right click in the water does an AoE stun that lasts about 10 sec. Their 'C' is a... Taunt? They also jump and you can fire a weapon from their back.
It's like a small Allo combined with a Kapro, in my opinion. Useful on both land & in the water. Use its secondary attack while swimming to stun, attack, and harvest. Does NOT stun Cnidarias, though, so do not expect to overpower them.