The Trakartan Tusked Lizards. As juveniles, both genders have long, thin spine protrusions connected with skin membranes, allowing them to glide short distances. The males grow thicker and heavier as they age, and eventually can no longer use the membranes for gliding. They are extremely aggressive, and protective of their territory. Violent fights and lack of use eventually tears away the membranes connecting their spikes. The females, who remain thinner and lighter, grow larger, colorful membranes, and remain able to glide throughout their lives, using the ability to escape danger.
June 2006. Pencil, Photoshop. Creature of the Week entry over at Conceptart.org.