The snow leopard is the closest modern-day relative of P. blytheae.Credit: Dennis Donohue / Shutterstock Despite their charisma, big cats remain a mystery in evolutionary terms. But a new study fills in some of the blanks, describing how a now-extinct species pushes the evolution of big cats back millions of years and relocates their origins to an entirely different continent than once believed. The term "big cats" usually refers to pantherine species, which includes lions, tigers, jaguars and leopards. And while any novice can tell these species apart based on outward appearances, the skeletons of these cats are extremely difficult to distinguish. Without a lion's mane or a tiger's stripes, even experts have trouble telling them apart. Thus, when paleontologists found a crushed but nearly complete skull of a big cat in Tibet in 2010---a rare find for this part of the world---it took researchers years of analysis to determine that it represents a now-extinct species.