Late Pleistocene Environmental Change Interpreted from δ\u3csup\u3e13\u3c/sup\u3eC and δ\u3csup\u3e18\u3c/sup\u3eO of Tooth Enamel from the Black Creek Swamp Megafauna Site, Kangaroo Island, South Australia

Stable carbon and oxygen isotope ratios of tooth enamel carbonate were collected from both fossils (50–100 ka) Tammar Wallaby (Macropus eugeneii) and Western Grey Kangaroo (Macropus fuliginosus) from a Late Pleistocene fossil deposit situated on Kangaroo Island, South Australia. δ13C and δ18O data were also obtained for modern equivalents of both species located proximal to the excavation site. Trace element compositions were collected for Sr, Ba, V, Cu, Zr, Y, La, Ca, Nd, and U for modern and fossil teeth, and for local soils. δ13C data for fossil kangaroo and wallaby range between − 5.0 and − 18‰, while less 13C enriched values between − 18 and − 25‰ are observed in modern tooth enamel. Early-formed molars are 13C depleted by 2.5‰ compared to late-formed molars, consistent with isotopic offsets observed in modern molars, and with offsets observed from preservation of original biogenic compositions. Overall, carbon isotopes indicate a shift in diet and environmental conditions from C4-inclusive mixed habitats (woods and open grasslands) during the Late Pleistocene, to C3-only wooded and closed canopy habitats today. δ18O values range between 23 and 30‰ and are indistinguishable for fossil and modern tooth enamel. Oxygen isotope compositions of plants and mammals correlate positively with local water compositions, and negatively with relative humidity. Thus, the lack of oxygen isotope differences for the Late Pleistocene vs. modern day teeth may be attributed to combined lower temperatures (decreasing local water δ18O) plus decreased relative humidity (increasing plant and mammal δ18O) in the Late Pleistocene. Trace element data from fossil and modern teeth and from fossil deposit sedimentary material indicate post burial chemical alteration. Excepting Ba and possibly Cu, concentrations of all other elements analysed (Sr, V, Zr, Y, La, Ce, Nd, and U) increased significantly relative to modern teeth (over an order of magnitude shift, with p ≤ 0.01 for t-tests and Mann–Whitney tests). This diagenetic process may have occurred during the Last Glacial Maximum (LGM), a period of localised wet conditions when significant amounts of soluble soil organic matter accumulated at the fossil site. Trace element analysis of local soils indicates that, relative to soils, teeth strongly prefer Sr and U [KD(fossil tooth/soil) 10], and exclude Zr, Cu, and possibly V and Ba [KD ≤ 0.5]. Surprisingly, Rare Earth Elements (REEs) indicate KD values of 1. These data imply that Ba is a poor indicator of chemical alteration, while Sr, U, Zr, V, Y, and REEs are particularly sensitive to alteration. Comparisons with other palaeoclimate data suggest that the environmental change on Kangaroo Island from Late Pleistocene to present was greater than on the Nullarbor Plain

Late Pleistocene megafauna site at Black Creek Swamp, Flinders Chase National Park, Kangaroo Island, South Australia

The occurrence of fossil vertebrate remains at Black Creek Swamp at the western end of Kangaroo Island, South Australia, along with reports of 'primitive' stone implements in the vicinity has, for more than seventy years, fuelled speculation that this site would reveal a definitive relationship between humans and megafauna. Radiocarbon dating in the 1970s and again in 2004 suggested accumulation at around the last glacial maximum, making it potentially the youngest megafaunal deposit in Australia. Our excavations produced no artefacts and no evidence of butchering. Taphonomic evidence indicates three phases of drought accumulation around an ephemeral water source. These droughts may have been induced by climate, sinkhole drainage, or both. The fauna includes 29 species; one third of the species are extinct. This component is represented by browsing herbivores and their putative predator, Thylacoleo carnifex. The extant species indicate a mosaic of habitats including open sclerophyll forest, grassy patches, areas of shrubby understorey and semi-permanent water sources. The occurrence of two dwarfed species is suggestive of isolation and resource depletion. Multiple dating techniques (OSL, ESR, U-series and14C) revealed a complex geochemical history for this site. New age estimates place the fossil accumulation between 110 and 45 ka

The earliest burst of necrophagous dung beetles in South America revealed by the Cenozoic record of Coprinisphaera

New ichnological, sedimentological and palaeobotanical information from a Miocene palaeosol succession from Patagonia bearing abundant fossil brood balls of dung beetles (Coprinisphaera) allow inferring novel aspects of the evolutionary history, biology and feeding habits of Scarabaeinae, along with the palaeoenvironmental and palaeoclimatic conditions in which they nested. Coprinisphaera tonnii and Coprinisphaera akatanka, both attributed to necrophagous dung beetles, represent 40.2% of the specimens. Considering their scarce or null record in older Cenozoic units from South America, these high values reveal that the first burst of necrophagous Scarabaeinae took place during the Miocene. Some Coprinisphaera preserve characters that indicate the developmental stage of the ball occupant and the adult emergence success. Both ichnospecies show the egg chamber isolated from the provision chamber, which was associated with a higher preference of cleptoparasites for necrophagous balls. The comparison among the abundance of traces of nest intruders in Coprinisphaera attributed both to necrophagous and to coprophagous beetles from different units of South America indicates that the presence of such intruders would be independent of the nature of the organic matter contained within the balls. Phytolith analyses performed in Coprinisphaera and extant necrophagous and coprophagous balls indicate that the comparison between the relative abundance of phytoliths in the wall of the brood ball, their infilling and the bearing palaeosol is a useful tool for inferring the feeding behaviour of the trace makers and support the attribution of Coprinisphaera tonnii and Coprinisphaera akatanka to necrophagous Scarabaeinae. Sedimentary and palaeosol analyses indicate that the beetles would have nested in well-drained soils showing mollic-like features, in grass-dominated habitats, under a seasonal sub-humid, temperate–warm climate.Fil: Cantil, Liliana Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bellosi, Eduardo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Sánchez, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gonzalez, Mirta Gladys. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Genise, Jorge Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

A New Late Hemingfordian Vertebrate Fauna from Hawk Rim, Oregon, with Implications for Biostratigraphy and Geochronology

The Hemingfordian North American Land Mammal Age is not well sampled, especially in the Pacific Northwest. Here we present both a description of a new fauna and two radiometric dates, 16.26 Ma and 16.44 Ma, constraining the Hawk Rim locality of central Oregon. Hawk Rim represents the first diverse late Hemingfordian fauna in the Northwest and is one of the stratigraphically lowest fossiliferous outcrops of the Mascall Formation. Much of Oregon was blanketed by Columbia River Flood Basalts during late Hemingfordian time, limiting not only outcrops but places for organisms to have survived. The site yields a taxonomically rich fauna sharing strong faunal similarity with the type locality of the Mascall but also containing taxa new to the formation and region. We describe occurrences of five genera of Artiodactyla, four genera of Perissodactyla, three genera of Rodentia, and six genera of Carnivora, with all but three new occurrences for the Hemingfordian of the Pacific Northwest. In particular, the carnivore fauna extends the geographic and temporal range of several carnivorans, and we describe a new hypercarnivorous mustelid, Watay tabutsigwii