Animals of Ashfall

The Ashfall water hole drew creatures of all descriptions to its muddy banks. Some would probably look strange to modern eyes. Some would resemble familiar creatures that still walk the Earth.

Some came to drink. Some came to wallow in the mud. Some came to bathe in the still, shallow water. None expected to perish in thick clouds of volcanic dust that swept over their world, ended their lives, and transformed their bodies into what paleontologist Bruce MacFadden described as a Lagerstätten or “mother lode” of specimens.

Thanks to the abundance of skeletons, the excellent preservation, and the mostly undisturbed positions of these bodies, it’s possible to envision how the animals of Ashfall might have looked when alive.

Here are some of the Ashfall animals, shown with their common names and some artistic imaginings of how they looked. Click each card to find out more about these creatures who lived and died together. Art is © Mark Marcuson/University of Nebraska State Museum

Animals from the Ash Bed

Barrel-bodied Rhino

Teleoceras major, Barrel-bodied Rhino

Teleoceras major

    Stood three and a half feet tall at the shoulder.
  • Grazing rhinoceros similar to a modern hippopotamus.
  • Barrel-chested, with a body that measured 10 feet around the belly.
  • Much shorter legs than a modern rhino.
  • Most likely semi-aquatic.
  • The most abundant large animal discovered at Ashfall.
  • Both males and females had a single small nasal horn.
  • Teleoceras means “perfect horn.”

Stout One-toed Horse

Pliohippus, Stout One-toed Horse


  • Similar in appearance to modern horse.
  • Largest single-toed horse found at Ashfall.
  • Probably good at running on grassland.
  • Considered a “missing link” in horse evolution that showed how horses went from having three toes to having one toe.
  • Had two long extra toes, but walked using only its main toe and was considered single-toed.
  • Related to modern horses, asses, and zebras.
  • Skull had pocket-like depressions near the eye sockets.
  • Plio in its name refers to the Pliocene Epoch, two to five million years ago, but changes in the geologic time scale moved it into the Miocene Epoch

Sturdy Three-toed Horse

Cormohipparion, Sturdy Three-toed Horse


  • Stood about three and a half feet tall at the shoulder.
  • Used all three of its toes.
  • Probably good at cornering because of side-toes.
  • Went extinct first in North America, then in Asia.
  • Ancestor of the Hipparion horses of Europe and Asia (three toed grazing horses).
  • Also called three-toed grazer.
  • Very complicated enamel pattern on its grinding teeth, good for chewing grass.
  • Cormo means “stem.”

Slender, Grass-clipping Horse

Protohippus, Slender, Grass-clipping Horse


  • Stood about three feet tall at the shoulder.
  • Similar in size to a donkey.
  • Had a smooth face without depressions in front of the eye sockets.
  • Front teeth were arranged in a straight line that made it easier to clip grass at ground level.
  • Had three toes but functionally was single-toed.
  • Probably ran fast on grasslands.
  • Ancestor to modern horses, asses, and zebras.

Browsing Horse

Hypohippus, Browsing Horse


  • Stood about three and a half feet tall at the shoulder.
  • Extinct species of three-toed horse.
  • Was nearly extinct at the time of the Ashfall cloud.
  • Larger in size but similar in bones and teeth to Mesohippus.
  • Short-crowned teeth were good for eating leaves rather than grass.
  • Shorter muzzle than most horses.
  • Eye sockets were far forward.
  • Hypo means “below.”

Small Three-toed Horse

Pseudhipparion, Small Three-toed Horse


  • Stood two and a half feet tall at the shoulder, about the size of a medium sized dog.
  • The most abundant type of horse found at Ashfall, as well as the smallest.
  • Had three toes, with well-developed side hooves extending downward on either side of the main hoof.
  • Had a shallow depression on its skull above the teeth on either side.
  • Was a grass-eater.
  • Also found in Asia.
  • Pseudhipparion means “false Hipparion,” referring to its resemblance to a different three-toed horse.

Ancestral Camel

Procamelus, ancestral camel


  • About five feet tall at the shoulder.
  • Females were smaller than males.
  • Found abundantly at Ashfall.
  • Ancestor of the modern one-humped and two-humped camels found in Africa and Asia.
  • One of at three least forms of camel found at Ashfall. (Aepycamelus and Protolabis were also found.)
  • Procamelus means “before” and “ancestral to.”

Secretarybird Mimic

Apatosagittarus, secretarybird mimic

Apatosagittarius terrenus

  • Stood about two feet tall.
  • A type of hawk, but with very long feet and legs compared to modern hawks
  • One of three bird species found at Ashfall that were new to science.
  • Named for its resemblance to the modern Secretarybird, a large bird with an eagle-like body and crane-like legs that lives on grasslands in Africa and stalks its prey on foot, chasing in a zigzag pattern.
  • Was not really related to the Secretarybird, but evolved similar characteristics due its similar grassland environment (evolutionary convergence).
  • Apato means “false” and terrenus means “belonging to the ground”.

Llama-sized Camel

Protolabis, llama-sized camel


  • Stood about three feet tall at the shoulder.
  • Smallest species of camel found at Ashfall to date.
  • Has similar appearance to a llama but is not a direct ancestor to llamas.
  • Narrow muzzle.
  • Strong lip and cheek muscles.
  • Had upper incisor teeth modern camel doesn’t.
  • Probably grazed on tough, shrubby vegetation.
  • Protolabis means “primitive lips.”

Racoon-like Dog

Cynarctus, Racoon-like Dog


  • Stood about a foot and a half tall at the shoulder.
  • First thought to be of the raccoon family but later was identified as an example of a bone-crushing dog.
  • Smaller than other bone-crushing dogs.
  • Jaws were slender.
  • Canine fangs and comb-type incisors that might have been useful for eating slippery frogs and salamanders.
  • Probably also ate small animals, insects, and fruit.
  • Cynarctus means “dog-bear.”

Saber-tooth Musk Deer

Longirostromeryx, saber-tooth deer


  • Stood about two feet tall at the shoulder.
  • Also called musk deer.
  • Had no horns.
  • Extinct but related to deer of the family Moschidae, still found in east Asia.
  • Elongated upper canine teeth earned the nickname “saber-tooth.”
  • Only males had saber-like canines.
  • Had a slender snout that fit into small spaces and allowed it reach tender plants.
  • Longirostromeryx means “long-snouted cud chewer.”

Animals from Below the Ash Bed

Round-tailed Beaver

Eucastor, round-tailed beaver


  • Two feet long, including the tail, about the size of a muskrat.
  • Much smaller than a modern beaver.
  • Had a rounded tail instead of a flat tail like a modern beaver.
  • Was the ancestor of much larger beavers, some as large as 500 pounds .
  • Only one specimen was found at Ashfall.
  • Eu means “true” or “typical,” and castor means “beaver.”

Thin-sabered “Cat”

Barbourofelis, thin-sabered cat


  • Specimen found in the sand below the Ashfall ash bed
  • Stood about one and a half feet tall at the shoulder.
  • Had short legs.
  • Was a carnivore.
  • Also known as false saber-toothed cats.
  • Not a good runner, so it probably ambushed its prey and killed victims with its sabers.
  • Teeth were good for stripping meat from bones, but not for bone breaking.
  • Not related to true cats but probably resembled the leopard, an ambush cat.
  • Barbourofelis means “Barbour's cat,” named to honor paleo sleuth E. H. Barbour.

Ancestral Pronghorn

Proantilocapra, Ancestral Prongbuck


  • Stood about one and half feet tall at the shoulder.
  • Pronghorns have lived in North American for 20 million years.
  • Long, slender legs enabled it to run faster than most land animals in the Western Hemisphere.
  • Sometimes called “antelopes” (incorrectly).
  • Had a permanent bony horn-core above the eye-socket rather than antlers like a deer.
  • Tall-crowned teeth good for tough grass and sage brush.

Fruit Dog

Carpocyon,Fruit Dog


  • Stood about 18 inches tall at the shoulder.
  • Blunt molar teeth that indicate it might have eaten fruit primarily.
  • Larger back molars were suited for crushing fruit, rather than slicing meat (as coyote’s teeth are).
  • Modern coyotes eat fruit when meat is scarce.
  • Did not have feet like modern dogs and was not a fast runner.
  • Carpos means “fruit” and cyon means “dog.”


Ischyrocyon, Beardog


  • Stood about three and a half feet tall at the shoulder.
  • Not an ancestor to bears or dogs.
  • Long, heavy tail.
  • Teeth suited to meat-slicing in its upper and lower jaws.
  • Walked flat-footed like a bear.
  • Unlike a modern dog, did not have long legs or feet good for running.
  • Ischyros means “strong” or “mighty.”

“Perfect Tusker”

Eubelodon, Perfect Tusker


  • Males stood about ten feet tall at the shoulder.
  • Weighs much heavier than a modern Asian elephant.
  • Also known as gompotheres.
  • Longer lower jaw.
  • Short tusks in its lower jaws.
  • The first elephant in Nebraska to develop big upper tusks.
  • Also was the first to develop a free-hanging trunk like a modern elephant.
  • Eu means “true” or “typical” and belodon means “arrow tooth.”

Giraffe Camel

Aepycamelus, Giraffe Camel


  • Stood about 11 feet tall at the head.
  • Not a true giraffe but part of the camel family.
  • Developed characteristics like a giraffe because its lifestyle was similar (convergent evolution).
  • Probably ate tree leaves.
  • Probably had a hard time drinking from the water hole.
  • Had fewer neck bones than a modern giraffe.
  • Aepycamelus means “high camel.”


Untermannerix, Moonrat


  • About five inches long, not including its tail.
  • Had tiny teeth with sharp points that allowed it to bite into the exoskeletons of insects.
  • Was nocturnal.
  • Had a hairless tail.
  • Modern descendants of the moonrat are related to hedgehogs and live in tropical forests in Southeast Asia.
  • Untermann is the name of a couple who were great supporters of paleontology, and erix means “hedgehog.”


Ustatochoerus, Oreodont


  • Stood about two feet tall at the shoulder.
  • Lived in small family groups.
  • Had short, flexible limbs.
  • May have climbed trees.
  • Had sharp front teeth that interlocked, good for cutting branches.
  • No close relative in modern times.
  • Used to be plentiful on the Great Plains.
  • Oreodont means “mountain tooth,” referring to the crested shape of its chewing teeth viewed from the side.


, Peccary


  • Stood two and a half feet tall at the shoulder.
  • Distantly related to Old World boars and domestic pigs.
  • Peccaries still exist South America, and some live as far north as Texas and Arizona.
  • Had canine tusks that pointed downward rather than tusks that curved upward like modern boars.
  • Was omnivorous, eating plants, nuts, roots, and small animals (live or dead).
  • Had cheekbones like a modern warthog, flaring outward.
  • Sthennops means “strong-looking” and refers to its skull.

Hornless Rhino

Aphelops, Hornless Rhino


  • Stood about three and half feet tall.
  • Was long-legged and proportioned normally, compared to Teleoceras (the other type of rhino found at Ashfall).
  • Was not a frequent visitor to the Ashfall water hole, which lacked the woody vegetation it usually ate.
  • Did not have a horn.
  • Had small tusks on its lower jaw.
  • Aphelops means “smooth-faced” or “hornless.”

Horned Rodent

Mylagaulidae, Horned Rodent


  • About one foot tall when standing on its hind legs, similar in size to a prarie dog.
  • Largest of the dozen species of rodents found at Ashfall.
  • A now extinct family.
  • Paleontologists still need to find good skull specimen at Ashfall for identification of this species, but teeth and bones have been found.
  • Huge claws
  • Was a digger that ate plant roots.
  • Mylagaulidae means “millstone bucket,” which refers to the huge grinding tooth it had on its lower and upper jaws.

Ashfall Fossil Beds

How did a volcano in Idaho turn a water hole in Nebraska into one of the richest deposits of fossil specimens ever found?

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