Super easy to kill these. Just stay behind them at their tails and attack. They only are able to defend their fronts. They only have one AOE attack that can hit all creatures in the area with projectiles, one purple cloud that acts as rare flower, and one that heats the area around to ignite ground foes. But they use those sparingly, and are easy to kill with Allosaurs and Rexes.
If you are on a “free build, missions disabled, fliers enabled official servers” you can kill them with Argies. Just attack their backs and tails. But watch for their buddies that might snipe you out of the air from a ways away.
If you get too close to a wild one that used it's special ability (a charge that will set it on fire and aggravate nearby dinos) it'll display a message saying "getting hot! Stay away!!!!" and that will set you on fire. Don't approach unless you know you're prepared.