Polyphyly, paraphyly, provinciality, and the promise of intercontinental correlation: Charles Repenning's contributions to the study of arvicoline rodent evolution and biochronology
"The science of systematics has long been affected by profound philosophical preconceptions, which have been all the more influential for being usually covert, even subconscious."
George Gaylord Simpson, 1953
We review the history of Charles A. Repenning's contributions to the study of arvicoline rodents, with emphasis on his philosophical approach to the study of fossils, their taxonomic affinities, biostratigraphic distribution, and biochronologic significance. Rep viewed these issues in an explicitly evolutionary context under which gradational and anagenetic change was accepted as the dominant mode of evolution. He recognized a polyphyletic origin of five independent arvicoline lineages, and viewed paraphyletic higher taxa within those lineages as some of the best evidence of evolution. That perspective, combined with his view that the rock record preserved an adequate material history of population-level evolution in arvicolines, led him to adopt taxonomic practices that can be confusing and cumbersome to non-specialists. He used fossils of arvicolines as tools to develop an intercontinental correlation scheme extending across North America, northern Asia, and Europe. A core component of his correlation scheme was the hypothesis of a bi-directionally balanced history of dispersal events across the Arctic Ocean borderland that introduced comparable arvicoline taxa into Europe and North America from source areas in Asia. Within North America, his biochronology was structured around a concept of immigrant taxa, although definitive establishment of immigrant status often was an elusive goal. He worked diligently to accommodate new data into his biochronologic framework, and was actively engaged with major conceptual issues at the time of his murder. Rep sought to integrate diverse data sets and to explain evolutionary events in the context of fine-scale geologic and climatic history. Those efforts led to his exploration and eventual adoption of independent biochronologies for different faunal regions. The establishment of diachronous boundaries of land mammal ages within North America remains one of his most controversial and thought-provoking proposals.
Key Words: Arvicolinae; faunal provinces; biostratigraphy; biochronology; paraphyletic
PE Article Number: 14.3.18A
Copyright: Society of
Vertebrate Paleontology November 2011
Submission: 15 June 2007. Acceptance: 5 October 2011