Foramen ovale as a new determinative sign for the identification of tiger (Panthera tigris) and lion (Panthera leo) skulls

Abstract

Tiger and lion bones are valued highly on the wildlife black market. The skeletons of the two species are very similar, but the level of protection and the laws applicable to them differ. When detecting crime in the field, it can be crucial to recognize the skeletons of these two species by their morphological features. A distinguishing feature neglected in practice is the foramen ovale at the base of the skull. A total of 112 skulls were evaluated (55 tigers and 57 lions). The orientation and appearance of the foramina ovalia were analyzed on skull photographs. Significant differences were found between tigers and lions. In lions, the foramina ovalia faced laterally and their outlets were usually at least partially hidden behind the straight edge of the os basisphenoidale from the ventral view of the skull. In most adult tigers, the foramina ovalia faced more rostrally with their outlets visible and bounded by a semi-circular edge of the os basisphenoidale. However, tiger skulls exhibited higher variability in foramina ovalia orientation than lion skulls. Like other identifying features on tiger and lion skulls, the foramen ovale was unable to distinguish all skulls with 100% confidence. Nevertheless, knowledge of this structure can help considerably in species identification.