Fenrir Skeletal Anatomy

 

Like most Athyrmatherians, an individual fenrir (Cynorhynchus lycanthropus) is not one, but multiple separate animals (or zooids) that attach in a single file line to form specialized tagmata, with the attachment being facilitated by a combination of specialized jaw and tail-derived couplers, tessellation, and an industrial strength airtight seal composed of a fibrous mucus. While this anatomy is extremely bizarre by the conventions of animals from Earth, it is par for course for these unique beasts, and is so well-developed that it would be nearly impossible to identify them as modular without any prior knowledge of their biology. What sets the fenrir and its relatives apart from other Euathyrmatherians, however, is their adaptations for pursuit predation. True to their genus name (Cynorhynchus = "dog beak"), fenrir have developed adaptations that largely mirror those of our own canids. Their thoracic and abdominal locomotor legs have extremely mobile shoulder bones that attach to the axial skeleton solely by muscle, and have lower limb bones that are slightly longer than the upper limb bones. They are also digitigrade, supporting a majority of their body weight on their phalanges without the actual foot bones making contact with the ground. The pelvic locomotor limbs emulate those of canids as well, even though what appear to be their thighs are actually modified "shoulders", and their "ankles" are actually elbows. The anterior and posterior tagmata of each zooid have a high range of up and down motion and a moderate range of side-to-side motion, allowing for the animal to gallop very efficiently. Their jaws, while weaker than those of the contemporary, more cat-like Cephalovenatorids, are nonetheless well-reinforced in order to withstand the stresses and forces of struggling prey, with a firmly anchored labrum (upper jaw) and stiffened joints in the gnathopods. The telson, which is usually made of a stiff rod of bone in other groups, is instead composed of more flexible cartilage in fenrir, and is used for both stability during pursuit and communication between pack members.