It was the late 1990s, and I was standing in front of the bathroom mirror of our childhood home, holding my dad’s solid-metal belt buckle up with a pseudo-serious expression on my baby face.

Regular tigers are intimidating enough as it is, but the fact that there was once something called the saber-toothed tiger walking around is pure nightmare fuel.

It’s almost impossible to picture a world where giant saber-toothed cats once prowled the earth. But that world was real, and ...