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Idaho SuperGraphic

The disappearing act

For more than 70 years, scientists have wondered why so many strange, horse-like fossils were found together in one locality. No one knows why so many animals died in the same place at approximately the same time. Research has provided two possible explanations as to what happened to the mysterious creature known as the Hagerman Horse, and why there is such a large concentration of ancient bones in the now famous Hagerman Horse quarry.


Traditionally, Gidley and other scientists thought that a lot of these strange creatures died around what was visualized to be a watering hole or bog. Gidley imagined individual animals coming to the watering hole to get a drink, dying, and then being buried in the mud surrounding the watering hole. Or instead of standing in a water hole, the animals may have waded out and stood in an ancient river. However, over the years, many inconsistencies showed up in the sample that was available for Gidley and other scientists to study.

The alternate explanation is that the concentration of mysterious horse bones represented a single herd that was catastrophically killed within a very short period of time. Research does show that there may have been a river, but the river dried up. The herd of animals flocked to the river to try and get a drink from the remaining water, ate all of the vegetation in sight and eventually either starved or died of thirst. This theory would explain how so many ancient bones ended up in the same area. This theory also coincides with what we know about certain modern-day species that scientists observe on the African savannah. Many species have seasonal migrations and risk losing their lives along the way, possibly while trying to cross flooded rivers in which many drown, are swept downstream and then quickly covered with silt.

Even though scientists have sound explanations for the treasure trove of ancient horse bones uncovered in the quarry, exactly what happened to the Hagerman Horse as an entire species still remains a mystery. What they do know, however, is that when significant environmental change occurs, most animals have three options: adapt, migrate or become extinct. Some ancestors of the modern-day horse did manage to migrate, but there was a mass extinction of the Hagerman Horse and scientists are still trying to figure out why. There are many factors that probably played a role in the disappearance of the horse, such as a dramatic fluctuation in climate and possibly the existence of prehistoric humans who may have relied upon these animals as a food source.

Related images

Modern scientists in the horse quarry
Scientists working in the horse quarry.
Courtesy of the National Park Service.

The evolution of Idaho's ancient savannah Hagerman treasure