Taxonomic and Ecological Functional Analysis of Modern and Fossil Southern African Rodent Postcrania
Abstract
Rodent remains found in many southern African Plio-Pleistocene fossil-bearing deposits are commonly used to reconstruct paleoenvironments using a taxonomic framework. In these studies, craniodental remains are the primary material used to reconstruct rodent paleocommunities while postcranial elements are generally not considered. Utilizing several different methods, this study tests whether analyses of African rodent postcrania can provide useful data for reconstructing past environments. First, this study tests if postcranial remains recovered in modern owl pellets can be considered isotaphonomic with recovered craniodental elements. Second, using both traditional linear measurements and two-dimensional outlines from digital photographs, this study tests if modern rodent postcrania can be used to identify what taxa (i.e. subfamily, genus and species) are present, and thus can be used in a similar manner as craniodental remains to reconstruct rodent community composition. Third, traditional linear measurements are also used to test locomotor habits exhibited by modern rodents within an ecological functional framework. Results from these analyses are then applied to fossil specimens from the hominin-bearing site of Swartkrans, South Africa. Results from this study show that rodent postcrania are as representative, or better, of the number of individual rodent prey items taken in modern owl roosts compared to estimates based on craniodental remains. Additionally, this study finds significant statistical support for the presence of ecological functional signals, as well as taxonomic signals at the family, subfamily, and genus level using rodent postcranial remains.
Classification rates, however, were generally low unless all postcranial elements included in this analysis were utilized. Rates for analyses of humeri and femora individually were not adequate for application to the fossil record with one exception. Outline based analyses of modern femoral form (i.e. shape + size) at the subfamily level classified correctly 90.1% of the time using linear discriminant function analysis with cross-validation. When these functions are applied to fossil rodent femora from Swartkrans two previously unidentified subfamilies, Cricetomyinae (pouched mice and rats) and Petromyscinae (rock mice), are recovered. The inferred habitat signal from the cricetomyines suggests a wooded component in Members 1 and 2, while that from petromyscines suggests a significant arid component in Members 1-3 during the period in which these deposits accumulated.
Citation
Campbell, Timothy Lee (2019). Taxonomic and Ecological Functional Analysis of Modern and Fossil Southern African Rodent Postcrania. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /188995.