These animals were very successful predators from a group known as creodonts. Their skulls show that they had incredibly strong jaws, and the males show grinding marks on their teeth very much like those of modern animals that use the noise of grinding teeth as an intimidation display.

PRONUNCIATION: HI-EE-NOH-DON
LIVED: 41 – 25 million years ago
SIZE: 4.6 feet tall at the shoulder and 10 feet long, plus tail
FACT: Carnivorous, with crushing jaws
MEANING: Hyena-toothed
CLOSEST LIVING RELATIVE: None; died out
RANGE: Asia and North America