42 



Curtis C. Bentley and James L. Knight 



Table 2. Location, sample size, and age of muskrat specimens. 



Locality 



Sample Size Age (y.b.p.) Source 



1-Mulen 3 



6 



500,000 



2-Kanopolis 



1 



500,000 



3-Hay Springs 



7 



350,000 



4-Anderson/Flohr 



2 



350,000 



5-Doby Springs 



11 



250,000 



6-Ichetucknee River 



23 



11,000 



7-Bell Cave Z3 



3 



20,000 



8-Bell Cave 1/2 



1 



15,000 



9-Yarbrough Cave 



2 



16,000 



10-Kingston Cave 



1 



10,000 



11-Louisiana 



31 



Recent 



12-Br. Columbia 



10 



Recent 



13-Nebraska 



10 



Recent 



14-New Jersey 



17 



Recent 



A-Crawfield 



5 



80,000 I 



B-Aucilla River 



15 



12-10,000 



C-Ardis L.F. 



18 



19,000 



D-Iowa 



22 



Recent 



E-Georgia 



2 



Recent 



Martin (unpublished) 



We believe the "dwarfing event" is an artifact of small sample 

 sizes and selection bias and not a dramatic evolutionary response to 

 some environmental change. However, further data are needed to provide 

 a more definitive answer to the true body mass trend of Ondatra zibethicus 

 during the latest Pleistocene. As fossil collections are amassed from 

 the latest Pleistocene a clearer picture may develop, resolving trends 

 that cannot be discerned here. 



ACKNOWLEDGMENTS— First and foremost we wish to thank 

 personnel of the Giant Cement Plant, Harleyville, South Carolina, for 

 their generous cooperation and patience while we worked in their 

 quarry. 



We also wish to recognize all those who toiled along with us 

 in the field: Vance McCollum, Linda Eberle, Craig and Alice Healy, 

 Derwin Hudson, Ray Ogilvie, Lee Hudson, Tom Reeves, Suzanne 

 Boehme, Martha Bentley, and Karin Knight. We are grateful to S. 

 David Webb and Gary Morgan, Florida Museum of Natural History, 

 Gainesville, Florida, for allowing us access to the University of Florida 

 collection and for critical reviews of this manuscript. Particular thanks 



