Thornies

Thornies are huge lizards the size of a crocodile, but high as a mid-sized dog.
Their upper bodies are completely covered in sharp and prickly thorns the size of a dagger, including the upper part of their legs and tails. The lower part of their bodies ar covered in thick scales.
Their feet have three fingers and another one opposed, all of them ending in claws that are similar to the rest of their thorns. They slip their claws in the end of chitin segments and crack insect armors open.
They are omnivore. They eat plants, roots and seeds when needed, but their favorite food is insects and other bugs.
They have developed immunity to poison, and capacity to spit a saliva that melts chitin, and makes it digestible by them. They are able to spit acid against giant insects, to weaken their thick armors, and when they bite an insect, saliva starts to flow, causing the insect armor to melt away.
Their legs are long, muscular and nimble, when hunting on when fleeing they can reach very high speeds in short ranges, sometime running using only their rear legs.
They can also roll themselves into a thorny ball, and roll for a while after running, or when the terrain has enough slope. A big heavy ball covered in daggers rolling fast against you is not something nice.
However, they rarely attack humans, they will usually flee from them. They will only attack to defend themselves, or if they are extremely famished. If they do, they will definitely use the acid spit and will claw and bite their enemies.