Inktober Monstrosities: R for Rock Reptile

You'd think finding a good monster for the letter R would be easy, it being the fourth most frequently used consonant in the alphabet, but as it turns out there were actually few good candidates on R. The final choice actually fell on this critter, the Rock Reptile.

They are described as horse sized lizards, living underground, with lumpy, warty hide, with chameleon like powers.