Beasts from The Great Migration
Inspired by our own world's natural history, the wildlife in The Great Migration was pulled almost entirely from the animals of the Eocene Epoch (56 million to 33.9 million years ago). With the extinction of the dinosaurs 10 million years earlier, the Eocene allowed for the first evolution of mammalian megafauna. Amazing beasts of all shapes and sizes appeared during this time and ranged across all the continents, except Antarctica. Some of the new families of animals, like family brontotheriidae, existed for the entirety of the Eocene Epoch.
Brontotheres
Massive herbivores, the largest brontotheres measure eight feet high at the shoulder and 16 feet long with an estimated weight at 3.5 tons (7000 lbs). They live solely in Thunder Valley in smallish herds that number up to 30 animals. Occassionally, many of these herds will merge together to form superherds, where younger animals might leave their family to live with a herd of a different territory.
While the old, young, sick, and weak animals are targeted by the hyenas, barongs, barbour cats, and other predators of Thunder Valley, a healthy, adult brontothere has little to fear from all, but the most aggressive of the barong clans. With a hide five inches thick in some places, indeed, there are few predators even capable of causing a wound to an adult brontothere! Thick faceplates anchor the twin, knobby horns that grow from a single base at the front of the animals' snouts. Primarily used by males to compete for breeding rights, these horns are also effective defensive weapons against the predators of Thunder Valley.
The brontotheres affect every aspect of Thunder Valley with their presence. After living among these animals for 2,000 years, the Zuni consider them sacred, and seek to preserve them and their habitat above all other life in the valley.
While they share their name with the hyenas of the outer world, the only similarity the hyenas of the Kingdom have to those animals are their teeth. Beyond that, these animals present a more primitive version of their foreign cousins, as well as a more savage one. It is speculated that the Kingdom's hyenas offer a look into the past, hinting at what the hyenas of the outer world used to be.
Hyenas and Barong
Unlike anything in the outer world, the barong of Thunder Valley strike fear into the hearts of humans and beasts alike. Up to four times larger than their smaller relatives, the barong are the most massive species of hyena to have ever existed, and the only predator known to prey on healthy, adult brontotheres.
Barbour Cats
The largest feline predator in the Thunder Valley, the barbour cats are a force to be reckoned with. Easily distinguished by their overgrown maxillary canine teeth, barbour cats live a largely solitary existence. They hunt by stealth, sprinting at high speeds to close the gap on their prey, and inflicting deep wounds at vital areas like the neck and belly. Male barbour cats can attain weights of 600 pounds or more, making them more than capable of defending their kills against the hyena clans with whom they share their territory.
Indricotheres
Prominently represented on Citizens' Arch, the towering indricotheres are the largest animals within the Kingdom's shores, and the largest land mammals to have ever existed. These creatures live in the southeastern region of the Kingdom and had historically presented a major threat to the farmlands of that area. At some point, the southeastern farmers figured out that indricotheres actively avoid any contact with bees, prompting them to surround their fields with domesticated beehives.
Terror Birds
The terror birds are found along the southern and southwestern regions of the Kingdom. More of a threat to livestock than people, they are the apex predators in these areas. Fast and endurant, these birds are favored by the artists of the southwest, and are often depicted in paintings, sculptures, and glass works.