Saber-toothed Cats - Ecology

Ecology

Why does the adaptation of saber-like canines come about at least four different times in different families such as nimravids, marsupials, and felids? The similarity in all these unrelated families involves convergent evolution of the saber-like canines as a hunting adaptation. Meehan et al. note that it took approximately 8 million years for a new type of saber-toothed cat to fill the niche of an extinct predecessor in a similar ecological role; this has happened at least four times with different families of animals developing this adaptation. Although the adaptation of the saber-like canines made these creatures successful, it seems that the shift to obligate carnivorism, along with co-evolution with large prey animals, led the saber-toothed cats of each time period to extinction. As per Van Valkenburgh, the adaptations that made saber-toothed cats successful also made the creatures vulnerable to extinction. In her example, trends toward an increase in size, along with greater specialization, acted as a "macro-evolutionary ratchet": when large prey became scarce or extinct, these creatures would be unable to adapt to smaller prey, consume other sources of food, and would be unable to reduce their size so as to need less food. The adaptations that would bring these creatures to apex predator status and dominance would lead them to their evolutionary doom.