Ancient Tracks Suggest Bone-Crushing Dogs Fed at Nebraska Ashfall Site

At Nebraska’s Ashfall Fossil Beds, researchers have found signs that wolf-sized prehistoric predators may have visited a watering hole while volcanic ash buried the animals gathered there. According to reporting by Phys.org, small tracks discovered in an ancient algae layer are believed to have been left by borophagines, an extinct evolutionary group commonly called bone-crushing dogs. The site also contains tooth marks on the bones of rhinos, horses and camels that appear to correspond to those predators. Additional evidence comes from coprolites, or fossilized feces, containing fragments of bone. Sam Matson, superintendent of Ashfall Fossil Beds State Historical Park, said the findings indicate that the animals fed on some of the creatures that died during the ashfall. Yet no skeletons belonging to the suspected scavengers have been found at the site. That absence leaves open the possibility that the animals survived long enough to eat from the watering hole before leaving, while their prey remained trapped. Researchers have not ruled out the discovery of their remains in the future, potentially in fossil dens. The fossils were preserved during an eruption about 12 million years ago in what is now southwestern Idaho. Geologists believe the eruption was roughly 1,000 times larger than the 1980 Mount St. Helens blast, spreading fine ash across the Great Plains. At Ashfall, near Royal, Nebraska, the deposit reaches roughly 8 to 10 feet thick, compared with about a foot across much of northern Nebraska. The site was once a seasonal watering hole. Evidence includes pond turtles, reed-like plant remains and microscopic organisms called diatoms. Larger animals initially endured the ash but gradually suffocated as it covered their food and filled the air, leaving their skeletons sealed in the deposit. Ashfall Fossil Beds became a state historical park in 1991 and remains an active excavation site. Fossils are studied where they were found, while researchers also use 3D scanning to document them. The current excavation area may provide another 10 to 15 summers of work, and new discoveries continue to emerge.