Hancock Mammal Quarry
Within the depths of the Clarno strata is a 40 million year old point bar, formed by the buildup of silt, sand, clay, and gravel traveling around the bend of an ancient stream. The seasonal flooding of Clarno’s semitropical forest washed away an incredible variety of dead animals and plants to the point bar, preserving a record of a diverse forest, rich with a variety of both plants and animals. Dozens of strange-looking beasts are fossilized in the Hancock Mammal Quarry including Haplohippus – small leaf-eating horses; huge rhino-like animals called brontotheres; and Acheanodon – bear-like creatures similar to modern pigs. The large scavenger Hemipsaladon feasted on the carcasses, while cat-like animals hunted prey here.
Dominant fossils found in this assemblage:
Filling the Role...
Protitanops was a brontothere, a
type of perssiodactyl (odd toed ungulate). Although it resembles a rhino it is
more so closely related to horses. It
had two knob-shaped horns that pointed straight up. This large brontothere would have spent its
time browsing on twigs and leaves, lumbering about the forest floor.
Hemipsalodon grandis was a large terrestrial carnivore that would have fed on slower herbivore mammals like Plesiocolopirus hancocki and Teletaceras radinskyi. It only lived in North America but had smaller Hyaenodontidae relatives that lived in warmer climates further south.
Epihippus gracilis was an odd toed ungulate (hooved animal) that is believed to have evolved from Orohippus, which continued the evolutionary trend of efficient grinding teeth. E. gracilis had three toes that gave it the edge of maneuverability as the environment at the time was thickly forested. Another horse lived alongside E. gracilis named Haplohippus texanus, which was more primitive than Epihippus.
Did You Know?
The best place to see the monument's fossils is inside the Thomas Condon Paleontology Center at the Sheep Rock Unit.