Table 1.

Muscle presence/absence between gray wolf (C. lupus) and domestic dog (C. familiaris)

MuscleC. lupus (n = 4)C. familiaris (n = 6)
Orbicularis occuliPP
  • “P” indicates that the muscle is always present; “V” indicates that the muscle is variably present; “A” indicates that this muscle is mostly present (see ref. 2).

  • * This muscle was absent in one of the wolf specimens.

  • This muscle was never present in the gray wolf as a separate muscle but instead appeared as a small tendon incompletely separated from the orbicularis oculi muscle.

  • This muscle was consistently present as an independent muscle in all specimens except for one, a Siberian husky, where it could not be located.