FACING SMILODON: A NEW RECONSTRUCTION OF THE APPEARANCE OF SMILODON FATALIS

Smilodon fatalis is the best known saber-toothed cat. It has often been reconstructed by artists and anatomists who presume that it closely resembled a modern conical-toothed felid, but with the addition of elongated canine teeth. However, saber-toothed canines do more than affect the distance to which this animal must gape to clear these teeth for making a bite. A greater gape means that there must be an increased mass of lip, mucosa and facial musculature surrounding the oral opening, although evidence for such soft tissues is not easily obtained from fossils. Here, we propose use of muscle scars and comparison with living species as a means of identifying facial features for reconstruction of soft tissues in extinct taxa. In living and extinct felids oral tissues are stretched to their maximum at full gape; however when relaxed, with the mouth closed, or open to less than full gape, these tissues would be of greater volume in a dirk-tooth than in a conical-tooth felid. It is likely that the upper lip in Smilodon would show a greater degree of sag than is typical for modern cats. Nasal soft tissues are not preserved in Smilodon, although past reconstructions assumed that the nasal profile is nearly vertical, as is the case in living species. We suggest, instead, that the nasal soft tissues in Smilodon are retracted to a degree commensurate with the retraction of the nasal bones. The lower incisor row of Smilodon is strikingly larger than in comparable-sized modern Panthera tigris, and would therefore need to be more voluminous to stretch over such teeth. It is also likely that the lower lip in Smilodon sagged; perhaps causing this felid to resemble a bloodhound more than a conical-toothed felid.