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Recent Progress and Future Prospects in Fossil Xenarthran Studies, with Emphasis on Current Methodology in Sloth Taxonomy

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Abstract

Among the several positive developments in xenarthran studies over the past 20 years have been the training of and active participation by many new researchers, prospecting of previously unexplored or poorly known localities in northwestern South America, pioneering and expansion of paleobiological studies, and revisiting of classic sites in Argentine Patagonia. While these developments have resulted in much new information, including description of new taxa, correlation with faunas previously known from the classic regions of Argentina and Brazil, and enhanced understanding of the modes of life of extinct vertebrates, there remain several areas of research that require more effort from our community. Among these are the need for improved descriptions and illustration of skeletal structures such as those of the auditory and basicranial regions of the skull and the vertebral and autopodial elements. Although perhaps the more difficult and less well-documented regions, much is to be gained for phylogenetic and taxonomic analyses by enhanced efforts in these regards, and several recent publications help provide standard references to their description and illustration. Also, as alpha taxonomy forms the foundation of higher-level analyses, more attention must be paid to intraspecific variation and the quality of specimens in the recognition of diagnostic characters in descriptions of new taxa. Critical assessment of such variation and specimen choice in several recently erected taxa is conducted here, with the goal of inspiring more cautious assessment of characters and relying on a population rather than typological approach in reaching decisions on potential new taxa.

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Acknowledgments

This contribution stems from the Keynote Address that I had the honor of presenting during the ICVM 11 meetings in Bethesda, July 2016. I thank MS Bargo and JA Nyakatura for suggesting me as the Keynote speaker and allowing me to expand here my views on aspects of xenarthran studies. I am grateful for the efforts of C Cartelle and an anonymous reviewer, whose thoughtful comments and suggestions improved the quality of the manuscript. I extend thanks to the following fellow xenarthrologists who encouraged me in the development of the ideas presented in this article: MS Bargo, C Cartelle, TJ Gaudin, HG McDonald, and SF Vizcaíno.

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  1. Department of Ecology and Evolutionary Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada

    Gerardo De Iuliis

  2. Section of Palaeobiology, Department of Natural History, Royal Ontario Museum, 100 Queen’s Park Crescent, Toronto, ON, M5S 2C6, Canada

    Gerardo De Iuliis

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De Iuliis, G. Recent Progress and Future Prospects in Fossil Xenarthran Studies, with Emphasis on Current Methodology in Sloth Taxonomy. J Mammal Evol 25, 449–458 (2018). https://doi.org/10.1007/s10914-017-9407-8

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