Restoration of the superficial facial musculature in nimravids

The size, shape and position of the mouth and sensory features such as the nose, eyes and ears in the nimravid barbourofelins are reconstructed. The earliest barbourofelin studied, Sansanosmilus, is the most similar to both pantherine and nonpantherine felids in sensory structure morphology. Through time, the species of the barbourofelin lineage diverge from felids with regard to facial features. Evolutionary trends include expansion of the nasal region, a more lateral orientation of the eyes and lowered position for the ears. Increased width and shortening of the muzzle accommodates the large oral opening required by the large gape of Barbourofelis, culminating in B. frickiwith eyes oriented laterally enough to reduce stereoscopic vision. The ear position in this species is also significantly lower than in the earlier barbourofelins or felids. This may reflect an anatomic compromise between sensory structure position and changes in relative size, shape and position of other skull features. These changes correlate with increased canine tooth length and increased gape, exemplified byBarbourofelis fricki. Cranial soft tissue structures are restored through scars of attachment on the fossil bones, and the proportions of these features to one another determined. New observations provide criteria for reconstructing soft tissue anatomy in extinct animals.