Hyaenadon

The hyaenodontids had been top predators since the extinction of the dinosaurs. They soon took advantage of the plains all over Eurasia and North America and, like many animals of this time, grew to enormous sizes.

Hyaenodon was particularly successful. There were seven or so species ranging from the size of a fox to that of a small rhino, roaming the plains that became the Mongolian Hsanda Gol formation.

Traits & Evidence
There were at least seven species of Hyaenodon found in Mongolia at this time,varying in size from fox-sized to the size of a small rhino. Those shown the most in Walking with Beasts are the largest - Hyaenodon gigas - which was about 1.4m at the shoulder.

The largest species of Hyaenodon probably didn't need to hunt in packs in order to bring down prey, but palaeontologists think that the smaller species may have had to act in packs like dogs do in order to kill some of the larger animals such as chalicotheres.

The teeth of Hyaenodon show distinct grinding patterns that are similar to those seen today in animals which make an intimidating grinding noise with them.

Fossils in the USA show little piles of white bone-filled dung belonging to Hyaenodon on top of the fossilised skeletons of herbivores. This shows that they tended to defecate on their kills, as some modern carnivores do today. This is usually done when the predator has eaten its fill but is trying to hide the smell of the carcass from scavengers so that they can return.

Appearance
We have no evidence of the colour of Hyaenodon, but like modern predators it was probably camouflaged. The colour scheme chosen was based on the thylacine or Tasmanian tiger which is a dog-like (but marsupial) predator living in a similarly arid environment in Tasmania. There were several species all living in the same area, so it is possible that they each had distinguishing coat colours to help tell the species apart.

Land of Giants
As a baby indricothere is being born at night, a pack of smaller Hyaenadon attack it and its mother, though the mother manages to fight them off.

One large Hyaenadon stalks along a line of rocks, looking for prey. Later, a herd of chalicothere (who are still browsing) are attacked by the lone Hyaenadon. It kills one chalicothere by savaging its throat, and eats the carcass while the other chalicothere flee. A herd of entelodont show up, prompting the Hyaenadon to defeceate on the carcass and grind its teeth in display, but ultimately it gives up the chalicothere meal to the larger group of animals.

After the dry season, as it begins to rain again, the same Hyaenadon chases an entelodont through the mud and rain.