Tough survivors have come to call these Gargantuan reptiles Spiny Lizards, I believe that Moloch sagittarius' closest known relative is the Australian Thorny Devil (Moloch horridus). Besides the obvious gap in size, most of the differences between Moloch sagittarius and its smaller relative lie in its thorns.
Despite its dangerous spines, Moloch sagittarius has proven an excellent mount for indirect combat. Its ranged attacks can wreak havoc in a pitched battle, particularly if other creatures are taking the enemy's attention. Just be sure to use a proper saddle, strap yourself in securely, and use extreme caution while mounting or dismounting.
Instead of being permanent parts of its skin, Moloch sagittarius' thorns are more like spines or quills that can be removed and regrown. In fact, it is even capable of shooting these spines from its tail as a method of self defense, and examination of these projectiles has revealed that they are coated in a lethal poison.