Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population

The world's last population of woolly mammoths (Mammuthus primigenius) lived on Wrangel Island persisting well into the Holocene, going extinct at ca. 4000 cal BP. According to the frequency of 'radiocarbon dated mammoth remains from the island, the extinction appears fairly abrupt. This study investigates the ecology of the Wrangel Island mammoth population by means of carbon, nitrogen and sulfur isotope analyses. We report new isotope data on 77 radiocarbon dated mammoth specimens from Wrangel Island and Siberia, and evaluate them in relation to previously published isotope data for Pleistocene mammoths from Beringia and lower latitude Eurasia, and the other insular Holocene mammoth population from St. Paul Island. Contrary to prior suggestions of gradual habitat deterioration, the nitrogen isotope values of the Wrangel Island mammoths do not support a decline in forage quality/quantity, and are in fact very similar to their north Beringian forebears right to the end. However, compared to Siberian mammoths, those from Wrangel Island show a difference in their energy economy as judged by the carbon isotope values of structural carbonate, possibly representing a lower need of adaptive strategies for survival in extreme cold. Increased mid-Holocene weathering of rock formations in the central mountains is suggested by sulfur isotope values. Scenarios related to water quality problems stemming from increased weathering, and a possibility of a catastrophic starvation event as a cause of, or contributing factor in their demise are discussed. (C) 2019 The Authors. Published by Elsevier Ltd.Peer reviewe

Late Pleistocene climate and proboscidean paleoecology in North America: Insights from stable isotope compositions of skeletal remains

This thesis uses the carbon, nitrogen, and oxygen isotope compositions of mammoth (Mammuthus) and mastodon (Mammut) skeletal remains to reconstruct paleoclimate and paleoecology in Late Pleistocene North America. Analytical methods, sampling strategies, environmental adaptations and seasonal behaviors of proboscideans were investigated. Reliable and reproducible results are crucial for a study of this nature. A persistent methodological problem in the isotope analysis of structural carbonate in bioapatite was solved by reacting bioapatite under “sealed vessel” conditions. Growth rate determinations are critical for designing sampling strategies and interpreting results. Histological and isotopic measurements demonstrated variations in enamel growth rates within and among teeth. Sequentially sampling through the enamel thickness can resolve shorter-term (weekly) isotopic variations, and sampling along the tooth height (especially on the inner enamel surface) can resolve longer-term (monthly or yearly) variations. Proboscideans adapted to the conditions of their local environments. Clovis-age mammoths in Arizona sought out C4 grasslands that “greened up” as a result of summer rainfall. In C3-dominated environments (Great Lakes and Western Canada), seasonal variations were larger in mastodons than mammoths, possibly because the latter exploited a greater number of microhabitats, averaging plant and drinking water isotopic compositions. Mammoths and mastodons occupied different environmental niches, but both consumed a wide range of resources and regional differences were evident. Woolly mammoths in Old Crow delayed the initiation of weaning relative to modern elephants, perhaps as a defensive adaptation to the increased predation risk and decreased food quality/quantity during long hours of winter darkness at this high latitude location. Potential consequences of delayed weaning, such as longer inter-birth intervals and greater maternal energy investments, may have increased the population’s vulnerability to climatic stress or human hunting. Isotope results for Clovis mammoths in the San Pedro Valley are consistent with a relatively warm and dry climate, but do not indicate severe drought. Regional differences in δ13C values of proboscideans from C3-dominated environments were minimal, but variations in δ15N may be related to spruce abundances and/or aridity. Latitudinal variations in proboscidean δ18O values correlate well with modern meteoric water isotope compositions, which indicates their potential for reconstructing past paleoclimatic conditions

On the importance of stratigraphic control for vertebrate fossil sites in Channel Islands National Park, California, USA: Examples from new Mammuthus finds on San Miguel Island

Quaternary vertebrate fossils, most notably mammoth remains, are relatively common on the northern Channel Islands of California. Well-preserved cranial, dental, and appendicular elements of Mammuthus exilis (pygmy mammoth) and Mammuthus columbi (Columbian mammoth) have been recovered from hundreds of localities on the islands during the past half-century or more. Despite this paleontological wealth, the geologic context of the fossils is described in the published literature only briefly or not at all, which has hampered the interpretation of associated 14C ages and reconstruction of past environmental conditions. We recently discovered a partial tusk, several large bones, and a tooth enamel plate (all likely mammoth) at two sites on the northwest flank of San Miguel Island, California. At both localities, we documented the stratigraphic context of the fossils, described the host sediments in detail, and collected charcoal and terrestrial gastropod shells for radiocarbon dating. The resulting 14C ages indicate that the mammoths were present on San Miguel Island between ~20 and 17 ka as well as between ~14 and 13 ka (thousands of calibrated 14C years before present), similar to other mammoth sites on San Miguel, Santa Cruz, and Santa Rosa Islands. In addition to documenting the geologic context and ages of the fossils, we present a series of protocols for documenting and reporting geologic and stratigraphic information at fossil sites on the California Channel Islands in general, and in Channel Islands National Park in particular, so that pertinent information is collected prior to excavation of vertebrate materials, thus maximizing their scientific value

Mammoth-hunter Camps in the Scandinavian North Sea Sector during the Late Weichselian?

Until recently, the general view of archaeologists was that southern Scandinavia was uninhabited during the last ice age, the Weichselian glaciation. It was thought that humans arriving from south would have met a wall of ice if they tried to penetrate into the area. Recent climate reconstructions and glaciological data, combined with recent faunal finds from the adjacent North Sea sector, promote the idea of a much more moderate and prosperous landscape with large, now submerged, plains accessible. Then this paper argues that large parts of the South Scandinavian North Sea sector were actually inhabitable during most of this glacial period, with extensive ice-free coastal zones even during the Last Glacial Maximum. It is difficult to believe that humans, already well-documented in the adjacent land areas, should not have known to inhabit and exploit such a rich resource zone. In addition to the paleoenvironmental data, ethnoarchaeological evidence is used to document that it was no problem for humans to kill large animals such as mammoths as some researchers have maintained. Furthermore, findings from excavations of mammoth-hunter sites, are used to argue that the large quantities of megafaunal remains fished up from the North Sea in recent years should be seriously considered as representing settlement material associated with mammoth-hunter camps dating from the second half of the Weichsel Glacial Stage. The central question is whether these North Sea faunal remains represent sites similar to the mammoth-hunter camps known from other parts of Europe and from Siberia? If that is the case, the Cultural Heritage management is confronted with a hitherto unrecognised problem

Multiproxy analysis of permafrost preserved faeces provides an unprecedented insight into the diets and habitats of extinct and extant megafauna

The study of faecal samples to reconstruct the diets and habitats of extinct megafauna has traditionally relied on pollen and macrofossil analysis. DNA metabarcoding has emerged as a valuable tool to complement and refine these proxies. While published studies have compared the results of these three proxies for sediments, this comparison is currently lacking for permafrost preserved mammal faeces. Moreover, most metabarcoding studies have focused on a single plant-specific DNA marker region. In this study, we target both the commonly used chloroplast trnL P6 loop as well as nuclear ribosomal ITS (nrITS). The latter can increase taxonomic resolution of plant identifications but requires DNA to be relatively well preserved because of the target length (∼300–500 bp). We compare DNA results to pollen and macrofossil analyses from permafrost and ice-preserved faeces of Pleistocene and Holocene megafauna. Samples include woolly mammoth, horse, steppe bison as well as Holocene and extant caribou. Most plant identifications were found using DNA, likely because the studied faeces contained many vegetative remains that could not be identified using macrofossils or pollen. Several taxa were, however, identified to lower taxonomic levels uniquely with macrofossil and pollen analysis. The nrITS marker provides species level taxonomic resolution for commonly encountered plant families that are hard to distinguish using the other proxies (e.g. Asteraceae, Cyperaceae and Poaceae). Integrating the results from all proxies, we are able to accurately reconstruct known diets and habitats of the extant caribou. Applying this approach to the extinct mammals, we find that the Holocene horse and steppe bison were not strict grazers but mixed feeders living in a marshy wetland environment. The mammoths showed highly varying diets from different non-analogous habitats. This confirms the presence of a mosaic of habitats in the Pleistocene ‘mammoth steppe’ that mammoths could fully exploit due to their flexibility in food choice

Multiproxy analysis of permafrost preserved faeces provides an unprecedented insight into the diets and habitats of extinct and extant megafauna

The study of faecal samples to reconstruct the diets and habitats of extinct megafauna has traditionally relied on pollen and macrofossil analysis. DNA metabarcoding has emerged as a valuable tool to complement and refine these proxies. While published studies have compared the results of these three proxies for sediments, this comparison is currently lacking for permafrost preserved mammal faeces. Moreover, most metabarcoding studies have focused on a single plant-specific DNA marker region. In this study, we target both the commonly used chloroplast trnL P6 loop as well as nuclear ribosomal ITS (nrITS). The latter can increase taxonomic resolution of plant identifications but requires DNA to be relatively well preserved because of the target length (∼300–500 bp). We compare DNA results to pollen and macrofossil analyses from permafrost and ice-preserved faeces of Pleistocene and Holocene megafauna. Samples include woolly mammoth, horse, steppe bison as well as Holocene and extant caribou. Most plant identifications were found using DNA, likely because the studied faeces contained many vegetative remains that could not be identified using macrofossils or pollen. Several taxa were, however, identified to lower taxonomic levels uniquely with macrofossil and pollen analysis. The nrITS marker provides species level taxonomic resolution for commonly encountered plant families that are hard to distinguish using the other proxies (e.g. Asteraceae, Cyperaceae and Poaceae). Integrating the results from all proxies, we are able to accurately reconstruct known diets and habitats of the extant caribou. Applying this approach to the extinct mammals, we find that the Holocene horse and steppe bison were not strict grazers but mixed feeders living in a marshy wetland environment. The mammoths showed highly varying diets from different non-analogous habitats. This confirms the presence of a mosaic of habitats in the Pleistocene ‘mammoth steppe’ that mammoths could fully exploit due to their flexibility in food choice