108 Thomas D. Beaver, George A. Feldhamer, Joseph A. Chapman 



1940), placement of the extra molar at the posterior end of the series 

 (Fig. 8) would be expected if the condition were an atavistic trait. 



Based solely on the age of certain anomalous skulls, dental and 

 cranial anomalies in the river otter did not appear to be detrimental to 

 the overall condition or survival of individuals. As noted, anomalous 

 animals more than three years of age were found. The carcasses were 

 not available to assess body fat or other indices of physical condition, 

 however, so this conclusion must remain conjectural. We suspect, 

 though, that in contrast to the possible detrimental effects of anomalies 

 on individual mantled howler monkeys, Alouatta palliata, and subse- 

 quent effects postulated for dominance relationships and population 

 dynamics (Smith et al. 1977), anomalies probably are of little impor- 

 tance in the population dynamics of the river otter. 



ACKNOWLEDGMENTS.— We thank Dr. William Newman, Pam 

 Askins and Denise Andrews, Radiology Department, Sacred Heart 

 Hospital, Cumberland, Maryland, for providing X-rays of the study 

 material. Dr. J. Edward Gates, Appalachian Environmental Labora- 

 tory, critically reviewed the manuscript, and an anonymous reviewer 

 provided helpful comments. This is Contribution No. 1284-AEL, Appala- 

 chian Environmental Laboratory, Center for Environmental andEstuar- 

 ine Studies, University of Maryland. Specimens were collected as part 

 of a study funded by Maryland Federal Aid in Wildlife Restoration 

 W-49-R. 



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