While fishing, are you sick of all the fish being scattered? If you bring this dino near the shore or on a boat where fish are near by and use the aggro mist, it will aggro the fish to come right to you in a big crowd!
Their “nice” gas might be the gas form of soothing balm. Also it’s effect is to reduce the stamina of everything caught in the “soothing” cloud. Also if it lays eggs why not make its crap soothing balm?
#1 best dino to raid deinonychus nests. It cannot be latched onto, it has decent health and the deinonychus are addicted to purple gas, just remember that the deinonychus will attack you as soon as you dismount a pachyrhino even if you use the gas and also they are slow as all hell.
These takes make an excellent starting mount, while being weaker than a trike it can pacify most animals smaller than a Rex, giving you a good escape from and hungry pack of raptors and can Agro animals using its other scent thing, which comes in handy in leading creatures into a trap. It is also a two seater and is faster than the trike.
I used a lvl 100 tame pachyrhino to tame my 140 megalosaurus :) the first tranq ride the rhyno (the farts keep everything else off you) after that surround with pillars and fart away til it wakes up and repeat!