Hi Patchy!
In your evolution description, you say 'The Maxilla has evolved to fill the predator niche by having the front two feet move to the sides of the body and develop a single tusk-like structure suited for breaking through the armor of the Estabils allowing them to eat the flesh.' I am a bit confused by this sentence. As you write it, it seems like the front two limbs move to the outer edges of the body, then they become a single predatory structure. Do you mean that each one becomes a single pokey weapon thing, or that the two limbs merge into a single thing held together at the top of the body? I would assume that you mean that the Maxilla has two attack claws (the term 'claw' works better than 'tusk', as a tusk is a type of tooth), but I want to stay true to your vision.