Sex determination in lions (Panthera leo, Felidae): A novel method of distinguishing male and female skulls

摘要

Examination of skulls and mandibles reveals a consistent and previously undocumented means of distinguishing sex in lions (Panthera leo), on the basis of a phenomenon unique among Carnivora. Male lions show a pattern of increased pore-like porosity in the maxillary region, superfi cial and proximal to the root of the upper canine teeth. Although some porosity is present in females, pores are less common, smaller, less obvious and primarily restricted to the bulge in the maxilla that marks the root of the upper canine tooth. Increased porosity (fi ne pores) is also a gender-independent feature of young individuals. This feature remains prominent throughout the lives of males, whereas porosity diminishes as females approach adult size. Juvenile male lions show a rapid increase in head size, correlated with the time immediately prior to dispersal from the natal pride. Specifi cally, increases in the rate of growth of cranial features, including the dentition and facial musculature are reflected in these changes. The rapid alteration of these features in maturing male lions indicates readiness to compete for social status with adult pride males. It is hypothesized that maxillary porosity is the anatomical correlate of this phenomenon.