Extinct Dire Wolf (Canus dirus) Fact Sheet: Physical Characteristics

Careful study of fossil bone or tooth anatomy yields much exact information
about placement and strength of muscles, tendons, ligaments, nerves, and blood vessels. In rare cases, skin and hair impressions or actual skin or hair remains. Body weight is more difficult to gauge because fat leaves no impression on the skeleton.

General Description

• A wolf quite similar to the modern wolf except for being heavier, with a broader and more robust skull. (Anyonge & Baker 2006) (Anyonge et al 2003)
  • Skulls show evidence of considerable enhancement for attachment of powerful jaw muscles
    • Cheek bones (zygomatic arches) greatly expanded
    • Crest down midline of skull (sagittal) is large
    • Occipital bone in rear of skull has prominent backwards projection
  • Some earlier studies (Merriam (1912) describe skull features that have little significance in the mechanics of the skull
• On average, similar in size to largest of living gray wolves; largest dire wolves would have been larger than living gray wolves. (Binder et al 2002) (Anyonge & Roman 2006)
  • Weights calculated to be 25% heavier than living gray wolves
• Estimates of weight should not be based on femur length, as in many previously published estimates. (Anyonge & Roman 2006)
  • Stress calculations based on cross-sectional measurements of the femur should be more accurate.

Teeth

• Canine teeth have greater bending strength than seen in living dogs of similar size. (Van Valkenburgh & Ruff 1987)
• Slicing teeth (P4, the carnassial) on upper jaw larger than those of modern gray wolves (Anyonge & Baker 2006)
• Slicing carnassial (M1) on lower jaw is similar to that of typical canids (Anyonge & Baker 2006)
  • Not as far back as in bone-crushing hyaena
• Wear patterns on teeth show some blunting, suggesting some bone chewing
  • Teeth not as worn down as seen in bone crushing hyaenas
• As in other carnivores studied, the pulp cavity inside teeth closes with age as dentine is deposited (Binder et al 2002)
  • Can be used to predict age up to 6 or 7 years.

Pelage

• Unknown, assumed similar to modern gray wolf.

•  Not much difference between male or female body and tooth sizes.

• In a study of extinct dire wolf skulls compared with an extinct bone-eating dog, modern large gray wolves from Canada and Alaska, and spotted hyaenas: (Anyonge & Baker 2006)
  • Out of 15 significant measurements, only 4 differed from modern gray wolves
  • Skull is flatter (as is modern gray wolf's) than a spotted hyaena's; probably weren't cracking bones like hyaenas do.
  • Muscle used for chewing and biting (temporalis) could generate more force than seen in modern gray wolves; perhaps had stronger killing bites
• Skull not domed like that of bone crushing dogs.
• Longevity: assumed similar to modern wolf - 6-8 years.

Turner & Anton (1997)
Anyonge et al. (2003)
Anyonge & Baker (2006)
Anyonge & Roman (2006)