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Caves, arvicoline rodents, and chronologic resolution
Christopher N. Jass
ABSTRACT
Fossiliferous sedimentary deposits provide opportunities for paleontologists to explore detailed questions about the past history of individual species and assemblages. Caves often retain data sets that allow for detailed investigations into site chronology, paleoecology, and local faunal history. Re-evaluation of the arvicoline rodent assemblage from Smith Creek Cave, Nevada, resulted in a taxonomic data set that potentially conflicts with the previously published site chronology. Specifically, identification of previously unreported taxa included possible records of Microtus meadensis and M. paroperarius. Also identified were 4-triangle morphotypes of Lemmiscus curtatus. Smith Creek Cave is
one of few known localities to preserve a 4-triangle morphotype of L. curtatus. The possible occurrences of M. meadensis and M. paroperarius in one of the lowest sedimentary horizons in Smith Creek Cave (the reddish-pink silt zone) are particularly significant given the known chronologic distribution of these taxa (between 820 Ka and 146.02 ± 2.584 to 153.7 ±
6.4 Ka). A revised age estimate for the reddish-pink silt zone, based on known chronologic ranges of M. meadensis and M. paroperarius, would be markedly different than the published radiocarbon age for those sediments (28,650 ± 760 14C yr BP). The chronologic quandary between age estimates re-emphasizes the complex nature of paleontological and archaeological accumulations in cave deposits.
Christopher N. Jass. Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, 78712, and Vertebrate Paleontology Laboratory, The University of Texas at Austin, J.J.
Pickle Research Campus, 10100 Burnet Road, Building 6, Austin, Texas, 78758, USA
Present Address: Quaternary Paleontology Program, Royal Alberta Museum, 12845 –
102 Ave., Edmonton, Alberta, T5N 0M6, Canada
KEY WORDS: Arvicoline; Microtus; chronology
PE Article Number:
14.3.40A
Copyright: Society of
Vertebrate Paleontology November 2011
Submission: 15 June 2007. Acceptance: 18 March 2011 |