The egglutton replaced its ancestor the boneripper. With so many other predators around it changed it diet to only eggs. This resource was currently untapped. Its body has become big and fat with a huge mouth. In one gulp it can devour an entire nest thus allowing it to "gulp and go". If confronted by the parent of the eggs it has strong front legs with sharp claws as well as a big mouth full of teeth. It also has developed thicker skin in case it gets injured. Its tail now forms a strong back leg to help it walk on the riverbanks. It hardly swims anymore but will wade in the water to steal from nest on the river's edge.
It eats mostly hard-shelled eggs of other species but will sometimes eat rival egglutton eggs as well. It is not as smart as its ancestor and lack social skills. Basically all it likes to do is eat and mate, and then eat again. To keep from dying out it lays eggs year round since some eggs are bound to eat eaten by rivals. Its strong arms can tear down a burrow which may be filled with precious eggs. Its huge nostrils can smell eggs from miles away.