Location: Antelope County, northeast Nebraska
Time: 11.8 million years ago, during the Tertiary period
About this Famous Find: The fossils at Ashfall Fossil Beds represent a catastrophic death assemblage of Miocene (early Clarendonian) animals buried in volcanic ash. Evidence shows that the intact skeletons of barrel-bodied rhinos, three-toed horses, llama-sized camels and saber-toothed deer died in a waterhole after a supervolcanic eruption. The volcanic ash has been traced to the Bruneau-Jarbidge Eruptive Center in southwest Idaho. Fossil bone shows evidence of lung-damage-induced pathology, indicating that the animals survived for weeks before their demise. Three-dimensional preservation of fully articulated skeletons is common at the site. Preservation of cartilage, in-utero bone, coprolites, tracks, grass seeds, and invertebrate burrows is also evident.
Dozens of skeletons recovered in 1978-1979 are stored in the Vertebrate Paleontology Research Collections of the University of Nebraska State Museum. The Ashfall Fossil Site has been protected as a State Historical Park since 1991. Fossil skeletons are exposed and left in situ in the 17,500-square-foot Hubbard Rhino Barn where the public can view excavations on a seasonal basis.
Mammals found at the site include Teleoceras major, Pseudhipparion gratum, Cormohipparion occidentale, Neohipparion affine, Pliohippus pernix, Protohippus simus, Procamelus grandis, Protolabis heterodontus, Longirostromeryx wellsi, Cynarctus voorhiesi, and Leptocyon sp. Two birds, Balearica exigua and Apatosagittarus terrenus, and two reptiles, Hesperotestudo and Chrysemys sp., are also represented.
Parks (2 listings)
Ashfall Fossil Beds State Historical Park: This park preserves a fossil site formed when volcanic ash fell about 12 million years ago, covering the savannah-like grasslands of northeastern Nebraska. The park offers interpretive displays, a fossil preparation lab and educational programs.
NebraskaStudies.org: Ashfall: This site describes the origins of the Ashfall Fossil Beds, its discovery and preservation.
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Museums (1 listing)
University of Nebraska State Museum: This Lincoln, Nebraska, museum houses an estimated 7.5 million invertebrate fossil specimens and more than 85,000 cataloged vertebrate fossil specimens.
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