Resurfaced Tyrant

Completely immune to taunt mechanics.
If you are a pet class be prepared to take some damage or clear a route to kite.

Also regardless of profession this mob drops the
Long Regal Sinew which is a crafting reagent for the Leather working Tools of the Trade.
So if you haven't made it by now you can skip the dungeon farm as these are much easier to farm than Rezan.

You used to be able to farm monstrosities in Nazmir but Blizzard removed it from the loot table, apparently Blizzard just reused an old mob for this quest like they did when they reused the mob to make undead Rezan boss and forgot to disable the loot table.

I think either they fixed it a bit, or you were a bit mistaken. It's not immune to taunts, it's just that my pet didn't auto-taunt it, as it would normally do with other mobs, even with the ability marked as "auto-cast". As a hunter when I made my pet Growl, it did get aggro.

The following is copy/pasted verbatim from Tanisll's comment over on [npc=139709]'s page. Go over there and give that comment some upvotes too, if it was helpful to you! Presumably, these stomp sound IDs should all be the same, since these are the same model of dinosaur.

If you love the Risen Gargantuan pet but can’t stand the constant heavy stomping noise, you can silence it completely.

Step 1 – Get the stomp sound IDs
Normally you’d have to log them yourself with a sound ID addon like SoundID Locator, but I’ve already done that work. These are the stomp sound IDs:
803475
803477
803479
803481
803483
803485
803487
803489
803491
803493

Step 2 – Mute them
Install the MuteSoundFile addon. For each ID above:
• Enter the number in the “Sound ID (number)” field
• Click “Preview this sound” to confirm it’s the correct stomp sound
• Click “Mute this sound”
Repeat for all IDs.

Step 3 – Enjoy the silence
Once all 10 are muted, the Risen Gargantuan will walk quietly, no more ground-shaking thuds.