Document Type



Fossil mammals, Aftonian, Wisconsinan, Holocene, Zooarcheology, Paleoecology, Paleoclimatology


For over 115 years the Loess Hills region of western Iowa has furnished the fossils of Ice Age and recent mammals to both amateur and professional paleontologists. The oldest of these fossils (the "Aftonian fauna") predates the last glaciation and predominantly are the remains of large mammals. These sites are poorly understood but probably date from near the Irvingtonian/Rancholabrean boundary at about three quarters of a million years ago. The last glaciation (Wisconsinan) is represented by 3 micromammal-dominated faunas and scattered finds of individual specimens of large mammals. Taken together, these indicate rather open grassland, with scattered boreal forest groves which became more dense toward the end of the glaciation. Although cold by present-day standards, the climate must have been unlike any in North America today because the taxa are not now found living in association. The post-glacial (Holocene) began about 10,000 years ago and saw tremendous change in Iowa's fauna from the preceding Wisconsinan. Although no faunas are reported from the Loess Hills in the first two and half millennia of the Holocene, this period contains the extinction of the Pleistocene megafauna and the climatic warming which led to extirpation from the state of the more boreal micromammals. The rest of Holocene is represented by 20 sites, both paleontological and archeological, which document a smaller scale, but still distinctive, pattern of climate change. The foundations of this prehistoric record have been established but much work remains to be done to realize its potential as a predictive tool for future climatic change.

Publication Date

September 1986

Journal Title

Proceedings of the Iowa Academy of Science





First Page


Last Page



©1986 Iowa Academy of Science, Inc.



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