Answer: Panthera

Among all the 42 known cat species, big and small, in the Felidae family, there are only four that can roar. Specifically, the only roaring cats you’ll find—the lion, tiger, leopard, and jaguar—all belong to the genus Panthera.

What gives these four big cats the ability to roar is a voice box structure that differs from other cats. In the domestic cat (genus: Felis), for example, the voice box has a small bone called the epihyal bone. In the large cats of the Panthera genus, however, that bone has been replaced with a ligament.

The ligament can be stretched and, thanks to its flexibility, create a larger sound-producing passage as well as a wider range of pitch than is accessible to other cat species. Larger cats also have, courtesy of their size, larger vocal cords that lend them a deeper voice much in the same way that taller humans tend to have deeper voices.

Interestingly enough, even though lions and their cousins can roar, they cannot purr. The voice box structure that gives them the ability to roar replaced the bone structure that gives smaller cats the ability to purr nearly continuously.