Using Paleoclimate and the Fossil Record to Explain Past and Present Distributions of Armadillos (Xenarthra, Dasypodidae)

Abstract

Numerous climatic fluctuations occurred during the Cenozoic (last 66 Ma BP); some of them were drastic (e.g., during the Eocene-Oligocene boundary) while others were more gradual (e.g., late Tertiary cooling), but both have deep effect on the biotas. Armadillos are exclusively from the Americas; they have an old evolutionary history in South America and faunal replacement and/or local extinctions were detected, linked with climatic fluctuations. The global cooling of the late Eocene -early Oligocene coincides with a welldocumented faunal turnover of Dasypodinae by Euphractinae in Patagonia. During cold and arid periods of the Quaternary, Euphractinae and Tolypeutinae moved more than once to the eastern Pampean Region, and Dasypodinae moved northward to central Brazil or even further north to the Guyana Region. During interglacial periods some armadillos went extinct locally and/or moved to Patagonia (Zaedyus), central Argentina (Tolypeutes matacus, Chaetophractus vellerosus), or from the north to Mesopotamia and the Pampean Region (Dasypus). Since the end of the Pleistocene/early Holocene, human activity has strongly impacted armadillo populations. Currently, the eastern Pampean Region (Argentina) is characterized by the presence of the couple C. villosus -D. hybridus (probably established since the late Holocene), but during the Pleistocene was Z. pichiy -T. matacus while Z. pichiy -C. villosus characterized early-middle Holocene. This work serves as evidence that paleozoological studies can be used to assess responses of biological systems to large scale perturbations and is the basis for studying future species distribu-tions, in order to identify species in danger of extinction and establish management actions.

Diversity and disparity of sparassodonts (Metatheria) reveal non-analogue nature of ancient South American mammalian carnivore guilds

“…Other possible hypocarnivores include armadillos, particularly euphractines, which are more omnivorous than other extant armadillos and are known to catch and eat vertebrates [ 55 ]. Euphractines were the predominant armadillos during much of the Cenozoic [ 56 ], and some were apparently specialized for preying on vertebrates [ 57 ]. Armadillos may even have prevented sparassodonts from entering more omnivorous niches owing to ecological incumbency [ 58 ].…”

Phylogeography of screaming hairy armadillo Chaetophractus vellerosus: Successive disjunctions and extinctions due to cyclical climatic changes in southern South America

“…The Quaternary record of Euphractinae and Tolypeutinae shows displacements (expansions/contractions) to eastern Pampean Region that surely occured more than one time during glacial/interglacial cycles, probably in coincidence with glaciations and/or arid phases of the Holocene ([ 35 ] and references therein). Also Tonni [ 36 ] and Tonni et al [ 37 ] stated that the conditions during almost all the Holocene were of aridity/semiaridity and would have allowed the expansion of Patagonian and central Argentinean species as it had occurred previously during the Pleistocene.…”

Human occupation strategies and related environmental-climate during the middle and late Holocene in central Pampas of Argentina

“…The archeofaunal record shows the presence of species that are restricted to arid/semiarid environments. The association of Tolypeutes matacus and Zaedyus pichiy , which have been recognized in other Pampean sites during the middle Holocene, was interpreted based on their ecological requirements as indicators of arid and warm conditions within the framework of the middle-Holocene Thermal Maximum (Soibelzon, 2017; Soibelzon and León, 2017). The taxonomic diversity of rodents indicates an environmental probably characterized by grasses patches (e.g.…”