In 1968, remains of what were reported to be a larger-than-modern elk (Cervus elaphus) were recovered from terminal Pleistocene sediments associated with the Marmes Rockshelter archaeological site in southeastern Washington State. Originally thought to have been butchered by humans, it is associated with radiocarbon dates suggesting an age of about 9800 14C years B.P. Taphonomic analysis in 2009 indicates the elk likely died of natural causes during winter months; it was lightly scavenged by carnivores prior to burial from silt-rich spring runoff. The elk suffered from two pathological conditions: one resulting in fusion of the fourth and fifth cervical vertebrae, and the other resulting in excessive bone tissue on the proximal ends of the first ribs, seventh cervical, and first and second thoracic vertebrae. The Marmes elk is larger than modern Rocky Mountain elk (C. e. nelsoni) and is on the large end of the size range of modern Roosevelt elk (C. e. roosevelti). It is also larger than the similarly aged elk skeleton from Three Hills, Alberta. A single elk bone from the Sentinel Gap archaeological site in central Washington State, dated to about 10 200 14C years BP and located 130 km west of Marmes Rockshelter, is the same size as the same bone of the Marmes elk. Terminal Pleistocene elk in eastern Washington likely grew to exceptionally large size as a result of abundant grass at the time, forage that decreased in abundance as Holocene climatic conditions developed.