Chadronian Land Mammal Age, 38.0 to 33.9 million years ago
A Pig for All Seasons
Like other entelodonts (see this page), Archaeotherium zygomaticus (called Megachoerus when Matternes painted this mural) had a huge, bumpy skull and prominent fangs. It was about the size of a grizzly bear and was omnivorous, dining on live prey and carrion as well as roots and tubers. Although quite hoglike in many ways, entelodonts were not closely related to pigs.
Resting in the Riverbed
Early peccary Perchoerus (below) stands alongside a recumbent hornless rhinoceros known as Trigonias. This peccary remains a relatively rare fossil, with no complete skeletons known even today. Matternes made his “first attempt to restore Perchoerus” (right), as he wrote on the sketch, by modifying the skeleton of the Pliocene/Pleistocene peccary Platygonus (see this page).
Horselike Running Rhinos
Hyracodon was an early rhinoceros that bore little resemblance to its familiar modern relatives. Long-legged and slender, it looked more like a small horse than a living rhino. Its three-toed feet—clearly shown in the right-hand individual below—indicate that it was an odd-toed ungulate, or perissodactyl. The gridded sketch (right) was made in preparation for the final wall painting.
Small Shrubs Make the Scene
Matternes often painted small shrubs in the foreground of his landscape scenes that exemplified an area’s flora. Here a small Oregon grape (Mahonia) shrub is shown with its characteristic thorny leaves.
Scratching an Itch
The early camel Poebrotherium was small and graceful, and probably lived much as deer do today, browsing in a variety of environments. The beautiful coloration and evocative behavior envisioned by Matternes make Poebrotherium one of the more striking mammals in this mural.
“False” but Still Deadly
The “false” saber-toothed cat, Hoplophoneus, was not a true cat but did indeed bear lethally long canines. It represents an early evolution of saber teeth among carnivorous mammals (compare it to the later, independently evolved species shown on this page, this page, and 169). The pattern and texture of the animal’s fur appear distinctly feline, but Hoplophoneus had only distant affinities with cats.
A Miniature Meeting
In the image below, two tiny hoofed mammals (Leptomeryx, left, and Hypertragulus, right) meet beneath a shrub, unaware that Hoplophoneus (out of frame to upper left) has taken an interest in them. Both species were ruminants, like modern cows and camels, but they belonged to now-extinct lineages. They may have been somewhat similar to living musk deer and chevrotains (mouse deer) in their habits.
An Unlucky Lizard Becomes a Meal
The pebbly skin-armor of the lizard Helodermoides (below) afforded little protection against the jaws of Hyaenodon (right). Hyaenodon was one of the largest carnivores of its time, weighing as much as a gray wolf (about 100 pounds). Superficially doglike, it belonged to a now-extinct mammal family.
Giants on the Landscape
Brontotheres (or titanotheres) were some of the largest mammals of their time and were characterized by prominent, often forked nose horns (right). Although they bore a strong resemblance to modern rhinos, they were only distantly related to them. This herd of Megacerops (called Brontotherium at the time) guards a calf from outsiders, below.