User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5460283-20130921153335/@comment-17735225-20130924042746

I believe that it's not the particle of claws, but instead his powder beneath the scales around his body. My theory is that this Tigrex Rare is a Tigrex with extremely long exposure to heat from the volcano that it complete fused and changed some of its scale into explosive-rock-like powder. The powder will either be underneath the scale or between their gaps. The claw acts as flint stones but instead it doesn't directly cause explosion, the spark and vibration generated will activate the scale/powder on its body. The powder will then scatter into the air and act like time bombs (Like Uragaan's explosive rock thing).

The explosion will not damage Rex similiar to the reason why Uragaan doesn't hurt itself with explosive rocks.