The ecomorphology of southern African rodent incisors: Potential applications to the hominin fossil record.

Oliver C C Paine,Austin Lawrence,Nico Avenant,Matt Sponheimer,Daryl Codron,Jennifer N Leichliter,Cyril Charles

doi:10.1371/journal.pone.0205476

Oliver C C Paine, Austin Lawrence + Show 5 more

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https://doi.org/10.1371/journal.pone.0205476

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Abstract

The taxonomic identification of mammalian fauna within fossil assemblages is a well-established component of paleoenvironmental reconstructions. However, many fragmentary specimens recovered from fossil sites are often disregarded as they can be difficult to identify with the precision required for taxonomic methods. For this reason, the large numbers of isolated rodent incisors that are often recovered from hominin fossil bearing sites are generally regarded as offering little interpretive value. Ecomorphological analysis, often referred to as a “taxon-free” method, can potentially circumvent this problem by focusing on the adaptive, rather than the taxonomic significance of rodent incisor morphology. Here, we determine if the morphology of the upper incisors of modern southern African rodents reflects dietary behavior using discriminant function analysis. Our model suggests that a strong ecomorphological signal exists in our modern sample and we apply these results to two samples of isolated incisors from the hominin fossil bearing sites, Sterkfontein and Swartkrans.

Highlights

Fossil assemblages often contain elements that are of little or no interpretive value for traditional paleoecological investigations
These ratio measurements were used in our stepwise quadratic discriminant analysis (QDA) and a model was constructed that misclassified 37 of the 163 training specimens (22.7%; Fig 2 and Table 1)
Isolated rodent incisor morphology is a potential source of paleoenvironmental information

Summary

Introduction

Fossil assemblages often contain elements that are of little or no interpretive value for traditional paleoecological investigations. Methods relying on precise taxonomic identification of fossil specimens can rarely use fragmentary, or otherwise adiagnostic material Such is the case with most rodent-based reconstructions of hominin paleohabitats, which rely on the preservation of the molar tooth rows for species, genus, and/or subfamily-level identification (e.g., [1,2,3,4,5,6]). While such material exists, in many fossil localities there is often an abundance of isolated incisors that heretofore have been of little interpretive value due to their poor taxonomic control. Rodent incisors often freely slide in and out of the maxillary and premaxillary alveoli when soft tissue is lost after death—a major reason why so many are found

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