Skeleton - Ostaeology of the Wolf

On removal from the cooker, the skull was found to be whole, still containing cerebral matter, with the jaws still closed around the tongue, which washed loose during later cleaning. Teeth remained set in the jaw for two days after cooking before beginning to loosen in their sockets. (One of the upper sectorals was missing on original presentation.) No meat remained on the face. Remaining flesh was removed with scissors, knife, and hot water; the brain was washed out through the nostrils and the foramen magnum. Turbinate bones were observed in the nasal cavities. The skull (with mandible) was allowed to sit overnight in a bleaching solution, then dried in a commercial drying oven. The remaining bones had not been allowed to cook sufficiently (meat -- mostly tendon -- was still firmly fastened to them) and were cooked further in buckets of ammonia solution, removing the last of the flesh.

After removal from the oven, the skull was white, minutely pitted, and slightly greasy, with a large occipital crest and a heavy mandible with a high, wide and sturdy ascending ramus with deep pits for muscle attachment. The muzzle was blunt and wide, almost as wide as the rest of the skull. All bones were very thick and the skull quite stout overall. The remainder of the bones, once removed from the ammonia solution, were generally yellow and more greasy. Remains of tendon and meat continued to cling to the bones even after the ammonia bath. Dried tendon and other flesh continued to hold the vertebrae together, and the radius and ulna of both forearms were still fused, held together by thick interossial webbings of tendon.

The cervical (neck) vertebrae diminished in size from first to last and were compressed dorsolaterally. The first cervical vertebra was the atlas, which allowed the head to move up and down, and the second was the axis, which allowed movements of the head from side to side. The atlas was flattened vertically and had no spinous process but possessed two "wings" of bone spreading out to either side. The second, third, and fourth vertebrae had spinous processes and ventral crests (ridges of bone along their underside), with the most pronounced crest being in the axis, which had a thick "prong" extending forward to articulate with the atlas. The centrum of the axis was more markedly dished in the wolf specimen observed than in the coyotes or red foxes, although the dishing was present to some degree in all three species.

Thoracic vertebrae were much smaller than lumbar. Each vertebra had a number of small spines which projected anteriorly and posteriorly to articulate with nearby vertebrae, preventing extreme bending of the spinal cord and compression of the spine. The lumbar vertebrae increased in width from first to last and were compressed dorsoventrally. Large spinous processes were observed primarily on thoracic and lumbar vertebrae, pointing caudally on thoracic and almost anteriorly on lumbar. Thoracic vertebrae possessed only a limited articular process on the anterior sacrum but a wide, strong process on the base of the dorsal spine. There was a deep posterior notch beneath the spinous process, and the process itself was relatively wide and was "dished" concave anterior, which is typical for canids. The caudal vertebrae resembled the phalanges in shape and decreased in size to a single almost pointed bone at the distal end.

There were thirteen pairs of double-headed ribs, held to the sternum by long strips of cartilaginous flesh (the costochondral articulation), which survived after cooking as a series of long, slender, slightly flexible, cylinders of a yellowish substance. There were eight unfused sternebrae comprising the sternum.

None of the bones of the forelimb articulated with the axial skeleton in any way. The clavicle was a small, thin, triangular bony plate, cranial to the shoulder, which "floated" in the muscle of the chest. The lateral side of the scapula presented a high, wide diagonal spine, dividing the outer face of the bone into supraspinal and infraspinal fossa, and providing a place of attachment for the powerful shoulder muscles. A smaller ridge visible on the posterior lateral edge was the place of attachment of the teres major muscle. The cranial border was rounded, the posterior nearly straight. There was a strongly developed acromion process, which was not observed in the coyote or fox, and the metachromion was only slightly present. The scapula was longer in the wolf and coyote and more blocked-off and squarish in Vulpes.

The joint with the humerus was wide and only slightly concave caudoventrally. The two bones were attached with heavy bands of connective tissue which still clung to them after cooking. The humerus shaft was strongly curved convex cranially, with a slight spiral twist and an obvious deltoid ridge on the ventral side. There was no entepicondylar foramen on the distal end but there was a large supratrochlear foramen, which articulated with the coracoid process of the ulna.

The radius and ulna were bound together by interossial fascia and thus were incapable of lateral rotation (see forelimb articulation diagram at right). The radius was flattened caudocranially and increased in size distally, while the ulna diminished distally. The medial border of the radius projected distally, forming the styloid process at the end. There was a laterally concave facet (the ulnar notch) for articulation with the ulna; dorsally, there were three distinct grooves for the extensor tendons of the lower limb. The proximal end of the ulna formed a heavy blunt spike (the olecranon), which formed the wolf's "elbow" in life and had been protected by a heavy pad of flesh. It also served as the insertion site for several of the strong shoulder muscles. The coracoid notch was extremely deep and terminated proximally in a smooth-edged, pointed spike which slid through the supratrochlear foramen of the humerus during flexion of the limb. Because the radius and ulna were essentially fused, rotation of the forelimb was impossible in life.

The wrist (carpus) contained seven bones in two rows: three in the proximal row, four in the distal. There were five metacarpals, with the first one being much reduced (dewclaw). The bones of the other four metacarpals were similar in shape and diverged distally, with a concave palmar and convex dorsal surface. One of the carpals projected dorsocaudally, as an attachment for the muscles of the limb. The digits each contained three phalanges (except for the dewclaw, which had two). The proximate phalanges had nearly square shafts. The distal phalanges formed the claws: sharply curved scythes of bone sheathed in a sheet of keratin which wrapped around the bone and formed a hollow, dark hook which would constantly grow forward as it was ground down by wear. Two extremely small, round sesamoid bones were found at the rear of the distal ends of the metacarpals, their function unknown.

The pelvis was relatively long and thin and formed, more or less, a rectangle, articulating with the spinal cord via three fused vertebrae known as the sacrum. The sacrum was square and boxy and separated the lumbar from the caudal vertebrae. The acetabulum was a small, heavily concave medial, hemisphere, oriented ventrally and bounded medially by a flat plate of bone, which was thin to translucency. The obdurator foramen resembled an equilateral triangle with the corners rounded off. The ischial branch of the pubis was not everted; the symphysis was long and formed by both the ischium and the pubis. The wing of the ilium was slender in the wolf, and wider in the red fox and coyote.

The femur was relatively long and slender (compared to most mammals) and nearly cylindrical throughout its length. Many large muscles inserted on this bone and it was strongly marked by a medial and a lateral "rough line" down its shaft where the insertions were. The shaft was strongly curved in its distal two-thirds, convex cranially, but was straight vertically, with a flat surface at the distal end formed by the medial and lateral condyles. The proximal end was marked by three main protuberances: the greater and lesser trochanters (attachments for the haunch muscles) and the head (articulation with the acetabulum of the pelvis), which formed a near sphere and was very smooth, allowing great free movement of the hip joint. Two sesamoid bones were observed on the caudal face of the distal end. The left femur of the specimen was measured at 22.4 cm in length, with a central diameter of 1.7 cm.

The tibia articulated with the femur at another flat plate formed by a medial and lateral condyle on the proximal end. An intercondylar eminence fitted into the groove between the medial and lateral condyles on the femur. The fibula did not articulate with the femur at all and presented as a simple straight, flat, slender bone bonded to the tibia by two lateral tubercles, one on each end, without option for motion. The interossial space was largest in the fox and smallest in the wolf, with the distal end of the fibula running close alongside the tibia. The distal ends of the bones formed the lateral and medial malleoli, which articulated with the tarsals.

There were seven tarsals and four metatarsals, which diverged distally as did the metacarpals. There were four digits, each comprised of three phalanges, each terminating in a clawed toe reminiscent of the carpal digits. One metatarsal projected dorsocaudally as an attachment for the Achilles' tendon. Sesamoids appeared on the distal ends of the metatarsals.

Two known adult male specimens -- a coyote and a wolf -- possessed a bone interior to the penis -- the os penis, or baculum. This bone occurs sporadically in the animal kingdom and also appears in the domestic dog. In both canids it was hollow or dished down its length, possibly to contain the corpus spongiosum, with a distinct bend of approximately 20 degrees a little more than halfway down its length. The baculum diminished distally, with a thick base of roughened bone and a distal end which was little more than a point. The coyote baculum was less deeply dished than the wolf's and the edges of the hollow curved out, not inward as in the wolf. The wolf baculum was 13 cm long and 1.1 cm wide; the coyote's was 7.4 cm long and 0.7 cm wide. No adult red fox skeletons of known gender could be located. An immature male red fox skeleton was investigated, but no bone obvious as a baculum presented. Estes (1991) asserts that all Canidae have the bone.

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