Closely related to marsupials, this order of carnivorous metatherians never left South America, dying off before the ‘great American faunal interchange’ that introduced new mammals to the continent. Like marsupials, they gave birth to tiny young which sheltered in a pouch while they developed. Convergent evolution shaped many of them into near copies of placental mammals. Although most of them walked flat on their feet and were poorly suited to running, many could stand upright to grapple prey.
Borhyaena
Borhyaena was better suited to running than most of its relatives, although not to the extent seen in some marsupials and placental mammals. It would have still had to rely on ambush and stalking when hunting, and likely supplemented this diet with scavenging. It lived in Argentina and Chile during the middle Miocene.
Australohyaena was a close relative from late Oligocene Argentina which was both bigger and better adapted for crunching bone. Callistoe was about the same size as Borhyaena but even better adapted to running at the expense of losing some range of motion. Dukecynus is known only from fragmentary remains, but appears to have been similar to Australohyaena. It lived in Columbia during the mid Miocene. Lycopis had a wolf-like snout and lived in Argentina and Columbia during the middle Miocene.
Borhyaena
Proborhyaena
A massive, bear-like animal. Despite its bulk, it was an active predator with impressive fangs. It lived in Bolivia during the late Oligocene.
The closely related Paraborhyaena, also from late Oligocene Boliva, was almost as large. Arminiheringia wasn't closely related, but rivalled Proborhyaena in size and had similar anatomy. It lived in Argentina during the during the early Eocene.
Proborhyaena
For Paraborhyaena (250 lbs.) reduce ST and HP to 13. For Arminiheringia change bite damage to cutting.
Thylocosmilus
A saber-toothed predator which took it to an even more extreme level than Smilodon. Its mouth could hinge open wide enough to stab its oversized fangs straight into even the largest prey. These huge teeth were rooted above the eye-sockets and wrapped around the entire skull. The lower jaw had flanges to protect the tips. In overall body plan it mimicked the dirk-toothed cats, with strong fore-legs for grappling. It is known from Northern Argentina during the late Miocene and early Pleistocene.
Anachlysictis was a smaller relative from middle Miocene Columbia.