Sexual Dimorphism and Social Structure
Modern felids show sexual dimorphism, or differences in male and female morphology. The degree of dimorphism is influenced by several factors, including competition between males for females. Lions, for example, have a high degree of competition for females. Because a single male controls a pride of many females, the largest and most powerful males are most successful. Tigers, in contrast, exhibit only a small amount of sexual dimorphism, with males being only slightly larger than females. Because single individuals tend to control their own territories males rarely come into contact and do not fight each other for mates.
Smilodon exhibits only a small amount of dimorphism. There is very little overall difference in size between males and females, and only a slight difference in the enlarged canines. Thus, it is believed that Smilodon shared a similar lifestyle and social structure to modern tigers, where males faced little competition for females. This suggests that Smilodon fatalis was solitary rather than a social big cat. Some authors have suggested that Smilodon fatalis would have lived ins mall family groups with a single mated pair and their cubs.