The wadjetsaur is a split from the frilled serpentsaur; it was pushed from the desert into the rain forest by its ancestor and the lack of large prey in the desert. The wadjetsaur's frills have developed advanced musculature and joints and can now be used to dig nests, climb slippery surfaces, regulate body temperature and be used as weapons. The wadjetsaur has also developed rudimentary internal ears using the webbing of its top head spikes, which no longer have sharp edges and have regressed to only one spike on either side of the head, to carry sound vibrations to them. Its snout has become slightly more tapered so that it can take smaller prey and the spike on its tail has split into a larger three-pronged spike. Its skin color has also changed to a violet color to better camouflage itself in the rain forest. Due to the lack of competition in the form of other predators of similar size, the wadjetsaur has grown larger than its ancestor, reaching full growth at 1.8 to an extreme of 2.6 metres long.
The wadjetsaur waits in ambush for its prey. It attacks by striking with fangs and claws in the case of smaller prey, while it latches onto larger prey with said fangs and claws, wraps itself around the prey and stabs it with the spikes on its tail. It will then rip meat off of larger corpses with its claws and teeth. It swallows smaller prey whole. It will happily eat fresh carrion and will take dead meat instead of eating the other scavengers...unless it's still hungry, of course.
The wadjetsaur males constantly roam in search of fertile females. The males use their frills to impress the females, and when the female chooses a mate from her suitors, the males leave to find other receptive females. The female will dig a nest under a tree and lay her eggs inside. The temperature of the eggs determines their sex when they hatch. The female will watch over the eggs and young until they reach about 0.8 metres long; a size that will give predators second thoughts. The young feed themselves during this time and will eat prey that is too small for adult wadjetsaurs and will also feed on the leftovers of kills that their mother makes.