Stratigraphy and Paleoecology of Pleistocene Deposits Associated with the Giant Ground Sloths Recovered from West Tarkio Creek Beds, Page County, Iowa
Ray, Harold A.
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The recovery of an adult and two juvenile individuals of the giant ground sloth Megalonyx jeffersonii in 2001 from the sloth site along West Tarkio Creek, Page County, Iowa, is unique. Two sediment cores were taken in order to examine the paleostratigraphy and paleoecology of the sediments associated with sloths. Analysis of the cores began with detailed soil and sediment descriptions. Carbon isotope, radiocarbon, particle grain size, and phytolith samples were extracted from the cores. Radiocarbon results indicate the age associated with the M. jeffersonii, in excess of 43,500 years before present, is significantly greater than once assumed. Analysis of the sediment portrays a landscape adjacent to a stream system that would periodically flood and inundate the area depositing local sands that are interbedded with finer sediments and possible paleosols. Phytoliths and carbon isotopes recovered near the sloth recovery horizon suggest an ecological system dominated by forests and sedge.