Dire hyenas (known to many as hyaenodons) are more fearsome than their smaller cousins. While hyaenodons won't turn down carrion as a handy meal, they much prefer to hunt for prey. A pack of dire hyenas rarely stops moving and hunting for anything other than sleep, mating, or food. Hyaenodons are 6 feet tall at the shoulder and often over 12 feet long. They weigh 900 pounds.