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Temporal genomic data hold great potential for studying evolutionary processes such as speciation. However, sampling across speciation events would, in many cases, require genomic time series that stretch well back into the Early Pleistocene subepoch. Although theoretical models suggest that DNA should survive on this timescale1, the oldest genomic data recovered so far are from a horse specimen dated to 780–560 thousand years ago2. Here we report the recovery of genome-wide data from three mammoth specimens dating to the Early and Middle Pleistocene subepochs, two of which are more than one million years old. We find that two distinct mammoth lineages were present in eastern Siberia during the Early Pleistocene. One of these lineages gave rise to the woolly mammoth and the other represents a previously unrecognized lineage that was ancestral to the first mammoths to colonize North America. Our analyses reveal that the Columbian mammoth of North America traces its ancestry to a Middle Pleistocene hybridization between these two lineages, with roughly equal admixture proportions. Finally, we show that the majority of protein-coding changes associated with cold adaptation in woolly mammoths were already present one million years ago. These findings highlight the potential of deep-time palaeogenomics to expand our understanding of speciation and long-term adaptive evolution. Siberian mammoth genomes from the Early and Middle Pleistocene subepochs reveal adaptive changes and a key hybridization event, highlighting the value of deep-time palaeogenomics for studies of speciation and long-term evolutionary trends.

Aim: Late Quaternary climate oscillations had major impacts on species distributions and abundances across the northern Holarctic. While many large mammals in this region went extinct towards the end of the Quaternary, some species survived and flourished. Here, we examine population dynamics and range shifts of one of the most widely distributed of these, the moose (Alces alces). Location: Northern Holarctic. Taxon: Moose (A. alces). Methods: We collected samples of modern and ancient moose from across their present and former range. We assessed their phylogeographical relations using part of the mitochondrial DNA in conjunction with radiocarbon dating to investigate the history of A. alces during the last glacial. Results: This species has a relatively shallow history, with the most recent common ancestor estimated at ca. 150–50 kyr. Ancient samples corroborate that its region of greatest diversity is in east Asia, supporting proposals that this is the region of origin of all extant moose. Both eastern and western haplogroups occur in the Ural Mountains during the last glacial period, implying a broader contact zone than previously proposed. It seems that this species went extinct over much of its northern range during the last glacial maximum (LGM) and recolonized the region with climate warming beginning around 15,000 yr bp. The post-LGM expansion included a movement from northeast Siberia to North America via Beringia, although the northeast Siberian source population is not the one currently occupying that area. Main conclusions: Moose are a relatively recently evolved species but have had a dynamic history. As a large-bodied subarctic browsing species, they were seemingly confined to refugia during full-glacial periods and expanded their range northwards when the boreal forest returned after the LGM. The main modern phylogeographical division is ancient, though its boundary has not remained constant. Moose population expansion into America was roughly synchronous with human and red deer expansion. © 2020 The Authors. Journal of Biogeography published by John Wiley & Sons Ltd We warmly thank the following museums, curators and people for access to samples: the late Andrei Sher, Severtsov Institute, Moscow; Andy Currant, Natural History Museum, London; Alfred Gardner, Smithsonian, Washington DC; R. Dale Guthrie, University of Alaska, Fairbanks; John de Vos, National Museum of Natural History (Naturalis), Leiden; Eileen Westwig, American Museum of Natural History, NY; Fyodor Shidlovsky, Ice-Age Museum, Moscow; Tong Haowen, Institute of Vertebrate Palaeontology and Paleoanthropology, Beijing; Mammoth Museum, Yakutsk; Geological Museum, Yakutsk; Paleontological Institute, Moscow; Royal Alberta Museum, Edmonton; Zoological Institute, Saint Petersburg; Museum of the Institute of Plant and Animal Ecology, Ekaterinburg. We thank our Yukon First Nation research partners for their continued support for our work on the ice age fossils of Yukon Territory. We are grateful to the placer gold mining community and the Tr'ond?k Hw?ch'in First Nation for their continued support and partnership with our research in the Klondike goldfields region; and the Vuntut Gwitchin First Nation for their collaboration with research in the Old Crow region. We would also like to thank Shai Meiri for help in drawing the map and useful discussion, Tony Stuart for access to radiocarbon dates, and Iris van Pijlen for laboratory assistance. This research was funded by NERC grant NE/G00269X/1 through the European Union FP7 ERA-NET program BiodivERsA. Funding for AMS dating was provided through NERC/AHRC/ORAU Grant NF/2008/2/15.

One major challenge in the study of late-Quaternary extinctions (LQEs) is providing better estimates of past megafauna abundance. To show how megaherbivore population size varied before and after the last extinctions in interior Alaska, we use both a database of radiocarbon-dated bone remains (spanning 25–0 ka) and spores of the obligate dung fungus,Sporormiella,recovered from radiocarbon-dated lake-sediment cores (spanning 17–0 ka). Bone fossils show that the last stage of LQEs in the region occurred at about 13 ka ago, but the number of megaherbivore bones remains high into the Holocene.Sporormiellaabundance also remains high into the Holocene and does not decrease with major vegetation changes recorded by arboreal pollen percentages. At two sites, the interpretation ofSporormiellawas enhanced by additional dung fungal spore types (e.g.,Sordaria). In contrast to many sites where the last stage of LQEs is marked by a sharp decline inSporormiellaabundance, in interior Alaska our results indicate the continuance of megaherbivore abundance, albeit with a major taxonomic turnover (includingMammuthusandEquusextinction) from predominantly grazing to browsing dietary guilds. This new and robust evidence implies that regional LQEs were not systematically associated with crashes of overall megaherbivore abundance.

A mammoth tusk contains an inner mineralized protein matrix of dentine and an outer layer of cementum. Enamel is only present on the tips of the tusks of young mammoths, and is worn away in older mammoths. Dentine is a mineralized connective tissue containing the inorganic component of dahlite [Ca10(PO4)6(CO3)H2O]. To determine the species from which ivory originated, often destructive methods are used. Raman spectroscopy is a non-invasive laser-based technique that has proven applications in the chemistry of mineralized tissue. Ivory and bone have similar biochemical properties. The aim of this study is to test the hypothesis that mammoth ivory is identifiable using Raman spectroscopy. Mammoth tusks were kindly loaned from the Natural History Museum, London, UK. All tusks were from the species Mammuthus primigenius discovered either in Lyakhov Islands or next to the Yenisei river, Krasnoyarsk (Siberia, Russia) and span the Pleistocene epoch, Cenerzoic era. The ivory was scanned with an inVia Raman micro spectrometer (Renishaw Ltd) equipped with a x50 objective lens and a 785nm laser. Spectra were acquired using line maps on cross sections of two samples, and individual spectral points were acquired independently at random or at points of interest on all samples. Data was analysed with principal component analysis (PCA) using an in-house Matlab script. To date, the results of this study establishes that well preserved mammoth ivory can be characterized through the comparison of peak intensity ratios between organic v(CH) collagen peaks and inorganic v(PO) hydroxyapatite peaks. Differences were observed in the hydroxyapatite peak from spectra acquired near the medulla of the tusk compared to the cortex. This suggests that the tusk is more mineralized towards the cortex compared to dentine found closer to the medulla. A comparison of the average data from each mammoth tusk demonstrated that the mammoth spectral ‘fingerprint’ remains similar for all samples, though there was some inter-variation in the mineralization of the tusks from mammoths of the same species. Further work in this study aims to compare the Raman spectra between mammoth and elephant ivory. This will have direct applications in archaeology, as the species from which an ivory sample is found could be identified without the need for more traditional, destructive techniques of valuable artefacts. Additionally, international trade regulations require proof of the species from which ivory is obtained. The information obtained in this study will be valuable in developing quick and non-destructive methods for the identification of ivory from an unknown origin.

Late Quaternary climatic fluctuations in the Northern Hemisphere had drastic effects on large mammal species, leading to the extinction of a substantial number of them. The giant deer ( Megaloceros giganteus ) was one of the species that became extinct in the Holocene, around 7660 calendar years before present. In the Late Pleistocene, the species ranged from western Europe to central Asia. However, during the Holocene, its range contracted to eastern Europe and western Siberia, where the last populations of the species occurred. Here, we generated 35 Late Pleistocene and Holocene giant deer mitogenomes to explore the genetics of the demise of this iconic species. Bayesian phylogenetic analyses of the mitogenomes suggested five main clades for the species: three pre-Last Glacial Maximum clades that did not appear in the post-Last Glacial Maximum genetic pool, and two clades that showed continuity into the Holocene. Our study also identified a decrease in genetic diversity starting in Marine Isotope Stage 3 and accelerating during the Last Glacial Maximum. This reduction in genetic diversity during the Last Glacial Maximum, coupled with a major contraction of fossil occurrences, suggests that climate was a major driver in the dynamics of the giant deer.

Late Quaternary climatic fluctuations in the Northern Hemisphere had drastic effects on large mammal species, leading to the extinction of a substantial number of them. The giant deer (Megaloceros giganteus) was one of the species that became extinct in the Holocene, around 7660 calendar years before present. In the Late Pleistocene, the species ranged from western Europe to central Asia. However, during the Holocene, its range contracted to eastern Europe and western Siberia, where the last populations of the species occurred. Here, we generated 35 Late Pleistocene and Holocene giant deer mitogenomes to explore the genetics of the demise of this iconic species. Bayesian phylogenetic analyses of the mitogenomes suggested five main clades for the species: three pre-Last Glacial Maximum clades that did not appear in the post-Last Glacial Maximum genetic pool, and two clades that showed continuity into the Holocene. Our study also identified a decrease in genetic diversity starting in Marine Isotope Stage 3 and accelerating during the Last Glacial Maximum. This reduction in genetic diversity during the Last Glacial Maximum, coupled with a major contraction of fossil occurrences, suggests that climate was a major driver in the dynamics of the giant deer.

The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted herbivore, widely distributed from western Europe to north-east Siberia during the Late Pleistocene. Previous studies associate the extinction of the species ~14,000 years before present to climatic and vegetational changes, and suggest that later survival of populations in north-east Siberia may relate to the later persistence of open vegetation in that region. Here, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes and mitochondrial DNA sequences to elucidate the evolutionary ecology of the species. Our dataset comprised 286 woolly rhinoceros isotopic records, including 192 unpublished records, from across the species range, dating from >58,600 14C years to ~14,000 years before present. Crucially, we present the first 71 isotopic records available to date of the 15,000 years preceding woolly rhinoceros extinction. The data reveal ecological flexibility and geographical variation in woolly rhinoceros stable isotope compositions through time. In north-east Siberia, we detected δ15N stability through time. This could reflect long-term environmental stability, and might have enabled the later survival of the species in the region. To further investigate the palaeoecology of woolly rhinoceroses, we compared their isotopic compositions with that of other contemporary herbivores. This analysis suggests possible niche partitioning between woolly rhinoceros and both horse (Equus spp.) and woolly mammoth (Mammuthus primigenius), and isotopic similarities between woolly rhinoceros and both musk ox (Ovibos moschatus) and saiga (Saiga tatarica) at different points in time. To provide phylogeographical context to the isotopic data, we analyzed 61 published mitochondrial control region sequences. The data show a lack of geographic structuring; we found three haplogroups with overlapping distributions, all of which show a signal of expansion during the Last Glacial Maximum. Furthermore, our genetic findings support the notion that environmental stability in Siberia had an impact on the paleoecology of woolly rhinoceroses in the region. Our study highlights the utility of combining stable isotopic records with ancient DNA to advance our knowledge of the evolutionary ecology of past populations and extinct species.

The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted herbivore, widely distributed from western Europe to north-east Siberia during the Late Pleistocene. Previous studies have associated the extinction of the species ∼14,000 calendar years before present to climatic and vegetational changes, suggesting the later survival of populations in north-east Siberia may have related to the later persistence of open vegetation in the region. Here, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes and mitochondrial DNA sequences to elucidate the evolutionary ecology of the species. Our dataset comprised 286 woolly rhinoceros isotopic records, including 192 unpublished records, from across the species range, dating from >58,600 to 12,135 14C years before present (equivalent to 14,040 calendar years ago). Crucially, we present the first 71 isotopic records available to date of the 15,000 years preceding woolly rhinoceros extinction. The data revealed ecological flexibility and geographic variation in woolly rhinoceros stable isotope compositions across time. In north-east Siberia, we detected stability in δ15N through time, which could reflect long-term environmental stability, and may have enabled the later survival of the species in the region. To further investigate the paleoecology of woolly rhinoceroses, we compared their isotopic compositions with other contemporary herbivores. Our findings suggested isotopic similarities between woolly rhinoceros and both musk ox (Ovibos moschatus) and saiga (Saiga tatarica), albeit at varying points in time, and possible niche partitioning between woolly rhinoceros and both horse (Equus spp.) and woolly mammoth (Mammuthus primigenius). To provide phylogeographic context to the isotopic data, we compiled and analyzed the 61 published mitochondrial control region sequences. The genetic data showed a lack of geographic structuring; we found three haplogroups with overlapping distributions, all of which showed a signal of expansion during the Last Glacial Maximum. Furthermore, our genetic findings support the notion that environmental stability in Siberia influenced the paleoecology of woolly rhinoceroses in the region. Our study highlights the utility of combining stable isotopic records with ancient DNA to advance our knowledge of the evolutionary ecology of past populations and extinct species.

Only five species of the once-diverse Rhinocerotidae remain, making the reconstruction of their evolutionary history a challenge to biologists since Darwin. We sequenced genomes from five rhinoceros species (three extinct and two living), which we compared to existing data from the remaining three living species and a range of outgroups. We identify an early divergence between extant African and Eurasian lineages, resolving a key debate regarding the phylogeny of extant rhinoceroses. This early Miocene (∼16 million years ago [mya]) split post-dates the land bridge formation between the Afro-Arabian and Eurasian landmasses. Our analyses also show that while rhinoceros genomes in general exhibit low levels of genome-wide diversity, heterozygosity is lowest and inbreeding is highest in the modern species. These results suggest that while low genetic diversity is a long-term feature of the family, it has been particularly exacerbated recently, likely reflecting recent anthropogenic-driven population declines., The authors acknowledge support from the Science for Life Laboratory, the Garvan Institute of Medical Research, the Knut and Alice Wallenberg Foundation, and the National Genomics Infrastructure funded by the Swedish Research Council and Uppsala Multidisciplinary Center for Advanced Computational Science for assistance with massively parallel sequencing and access to the UPPMAX computational infrastructure. We thank the Natural History Museum at the University of Oslo for providing the Javan rhinoceros sample. We thank the Museum of the Institute of Plant and Animal Ecology (UB RAS, Ekaterinburg) for providing the sample of Siberian unicorn. M.T.P.G. was supported by European Research Council (ERC) Consolidator grant 681396 (Extinction Genomics). E.D.L. was supported by Independent Research Fund Denmark grant 8021-00218B. A.C. was supported by an Australian Research Council Laureate Fellowship (FL140100260). T.M.B. is supported by funding from the ERC under the European Union’s Horizon 2020 research and innovation program (grant agreement 864203), grant BFU2017-86471-P (MINECO/FEDER, UE), “Unidad de Excelencia María de Maeztu” funded by the AEI (CEX2018-000792-M), Howard Hughes International Early Career, and Secretaria d’Universitats i Recerca and CERCA Programme del Departament d’Economia i Coneixement de la Generalitat de Catalunya (GRC 2017 SGR 880). L.D. was supported by the Swedish Research Council (2017-04647) and Formas (2018-01640)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2018-000792-M).

To understand the causes and implications of an extinction event, detailed information is necessary. However, this can be challenging when working with poorly resolved paleontological data sets. One approach to increase the data resolution is by combining different methods. In this study, we used both radiocarbon and genetic data to reconstruct the population history and extinction dynamics of the woolly mammoth in northern Siberia. We generated 88 new radiocarbon dates and combined these with previously published dates from 626 specimens to construct Bayesian age models. These models show that mammoths disappeared on the eastern Siberian mainland before the onset of the Younger Dryas (12.9–11.7 ky cal BP). Mammoths did however persist in the northernmost parts of central and western Siberia until the early Holocene. Further genetic results of 131 high quality mitogenomes, including 22 new mitogenomes generated in this study, support the hypothesis that mammoths from, or closely related to, a central and/or west- Siberian population recolonized Wrangel Island over the now submerged northern Siberian plains. As mammoths became trapped on the island due to rising sea levels, they lived another ca. 6000 years on Wrangel Island before eventually going extinct ca. 4000 years ago.

Summary Evolution on islands, together with the often extreme phenotypic changes associated with it, has attracted much interest from evolutionary biologists. However, measuring the rate of change of phenotypic traits of extinct animals can be challenging, in part due to the incompleteness of the fossil record. Here, we use combined molecular and fossil evidence to define the minimum and maximum rate of dwarfing in an extinct Mediterranean dwarf elephant from Puntali Cave (Sicily). 1 Despite the challenges associated with recovering ancient DNA from warm climates, 2 we successfully retrieved a mitogenome from a sample with an estimated age between 175,500 and 50,000 years. Our results suggest that this specific Sicilian elephant lineage evolved from one of the largest terrestrial mammals that ever lived 3 to an island species weighing less than 20% of its original mass with an estimated mass reduction between 0.74 and 200.95 kg and height reduction between 0.15 and 41.49 mm per generation. We show that combining ancient DNA with paleontological and geochronological evidence can constrain the timing of phenotypic changes with greater accuracy than could be achieved using any source of evidence in isolation.

Ancient DNA has significantly improved our understanding of the evolution and population history of extinct megafauna. However, few studies have used complete ancient genomes to examine species responses to climate change prior to extinction. The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted megaherbivore widely distributed across northern Eurasia during the Late Pleistocene and became extinct approximately 14 thousand years before present (ka BP). While humans and climate change have been proposed as potential causes of extinction [1–3], knowledge is limited on how the woolly rhinoceros was impacted by human arrival and climatic fluctuations [2]. Here, we use one complete nuclear genome and 14 mitogenomes to investigate the demographic history of woolly rhinoceros leading up to its extinction. Unlike other northern megafauna, the effective population size of woolly rhinoceros likely increased at 29.7 ka BP and subsequently remained stable until close to the species’ extinction. Analysis of the nuclear genome from a ∼18.5-ka-old specimen did not indicate any increased inbreeding or reduced genetic diversity, suggesting that the population size remained steady for more than 13 ka following the arrival of humans [4]. The population contraction leading to extinction of the woolly rhinoceros may have thus been sudden and mostly driven by rapid warming in the Bølling-Allerød interstadial. Furthermore, we identify woolly rhinoceros-specific adaptations to arctic climate, similar to those of the woolly mammoth. This study highlights how species respond differently to climatic fluctuations and further illustrates the potential of palaeogenomics to study the evolutionary history of extinct species. Here, Lord et al. sequence a complete nuclear genome and 14 mitogenomes from the extinct woolly rhinoceros. Demographic analyses show that the woolly rhinoceros population size was large until close to extinction and not affected by modern human arrival in northeastern Siberia. The extinction may have been mostly driven by climate warming.

The largest antlers of any known deer species belonged to the extinct giant deer Megaloceros giganteus. It has been argued that their antlers were too large for use in fighting, instead being used only in ritualized displays to attract mates. Here, we used finite-element analysis to test whether the antlers of M. giganteus could have withstood forces generated during fighting. We compared the mechanical performance of antlers in M. giganteus with three extant deer species: red deer (Cervus elaphus), fallow deer (Dama dama) and elk (Alces alces). Von Mises stress results suggest that M. giganteus was capable of withstanding some fighting loads, provided that their antlers interlocked proximally, and that their antlers were best adapted for withstanding loads from twisting rather than pushing actions, as are other deer with palmate antlers. We conclude that fighting in M. giganteus was probably more constrained and predictable than in extant deer.

DOI: 10.1016/j.quascirev.2016.06.007 URL: http://www.sciencedirect.com/science/article/pii/S0277379116302086 Filiació URV: SI Tooth wear analysis techniques (mesowear and microwear) are employed to analyze dietary traits in proboscideans, perissodactyls and artiodactyls from 33 Pleistocene localities in Britain. The objectives of this study are to examine the variability in each taxon, to track dietary shifts through time, and to investigate resource partitioning among species.The integration of mesowear and microwear results first allowed us to examine dietary variability. We identified differences in variability among species, from more stenotopic species such as Capreolus capreolus to more eurytopic species such as Megaloceros giganteus and Cervus elaphus. Broad dietary shifts at the community level are seen between climatic phases, and are the result of species turnover as well as dietary shifts in the more flexible species. The species present at each locality are generally spread over a large part of the dietary spectrum, and resource partitioning was identified at most of these localities. Mixed feeders always coexist with at least one of the two strict dietary groups, grazers or browsers. Finally, for some species, a discrepancy is observed between meso- and microwear signals and may imply that individuals tended to die at a time of year when their normal food was in short supply.

The giant deer, Megaloceros giganteus, is one of the most celebrated of late Quaternary megafaunal species. Here we present new radiocarbon data on the pattern of its extinction, and compare this, on a region-by-region basis, with evidence of environmental change and human occupation. Following strict auditing criteria for the acceptance of radiocarbon dates, 51 dates are published here for the first time, bringing the total number of accepted dates for the species to 134. For western Europe, extirpation around the start of the Younger Dryas stadial is corroborated. Previous early-to mid-Holocene records for the Urals and Siberia are augmented by new dates that together provide an almost continuous radiocarbon record from the late-glacial to the mid-Holocene. Newly-rediscovered skeletal material of giant deer from the Maloarchangelsk region of European Russia has provided the latest date for the species known so far, and extends the mid-Holocene range substantially westward almost to Ukraine. The relatively narrow overall distribution of M. giganteus through its history, and direct palaeoecological evidence, demonstrate the species’ requirement for a mixed, partially open habitat providing both graze and browse. Its extirpation from western Europe remains strongly linked to deterioration of climate and productivity in the Younger Dryas, while its disappearance from more eastern areas correlates chronologically with the spread of closed forest. However, these intervals also coincide with the arrival of (probably sparse) human populations in the regions occupied by giant deer in Ireland and across Russia. The pattern of distributional changes leading to the Holocene restriction of giant deer populations strongly suggests environmental causation, but a contribution of human hunting to the extirpation of terminal populations cannot be ruled out.

Understanding extinction events requires an unbiased record of the chronology and ecology of victims and survivors. The rhinoceros Elasmotherium sibiricum, known as the ‘Siberian unicorn’, was believed to have gone extinct around 200,000 years ago—well before the late Quaternary megafaunal extinction event. However, no absolute dating, genetic analysis or quantitative ecological assessment of this species has been undertaken. Here, we show, by accelerator mass spectrometry radiocarbon dating of 23 individuals, including cross-validation by compound-specific analysis, that E. sibiricum survived in Eastern Europe and Central Asia until at least 39,000 years ago, corroborating a wave of megafaunal turnover before the Last Glacial Maximum in Eurasia, in addition to the better-known late-glacial event. Stable isotope data indicate a dry steppe niche for E. sibiricum and, together with morphology, a highly specialized diet that probably contributed to its extinction. We further demonstrate, with DNA sequencing data, a very deep phylogenetic split between the subfamilies Elasmotheriinae and Rhinocerotinae that includes all the living rhinoceroses, settling a debate based on fossil evidence and confirming that the two lineages had diverged by the Eocene. As the last surviving member of the Elasmotheriinae, the demise of the ‘Siberian unicorn’ marked the extinction of this subfamily.

Analysis of the predictable breakdown of proteins and amino acids in ancient biominerals enables age estimation over the Quaternary. We postulate that enamel is a suitable biomineral for the long-term survival of endogenous amino acids. Analysis of multiple amino acids for geochronological studies is typically achieved using a RP-HPLC method. However, the low concentrations of amino acids coupled with high concentrations of inorganic species make accurate determination of amino concentrations challenging. We have developed a method for the routine preparation of multiple enamel samples using biphasic separation. Furthermore, we have shown that amino acids that exhibit effectively closed system behaviour can be isolated from enamel through an exposure time of 72 h to bleach. Elevated temperature experiments investigating the processes of intra-crystalline protein degradation (IcPD) do not appear to match the patterns from fossil samples, reinforcing the need for a comprehensive understanding of the underlying mechanisms of protein degradation. This novel preparative method isolates intra-crystalline amino acids suitable for the development of mammalian geochronologies based on enamel protein degradation. The lower rates of racemisation in enamel (cf.Bithyniaopercula) suggest that the enamel AAR may be able to be used as a relative dating technique over time scales > 2.8 Ma. Enamel AAR has the potential to estimate the age of mammalian remains past the limit of all other current direct dating methods, providing an invaluable tool for geochronological studies.

Plants and animals influence biomass production and nutrient cycling in terrestrial ecosystems; however their relative importance remains unclear. We assessed the extent to which mega-herbivore species controlled plant community composition and nutrient cycling, relative to other factors during and after the Late Quaternary extinction event in Britain and Ireland, when two-thirds of the region’s mega-herbivore species went extinct. Warmer temperatures, plant-soil and plant-plant interactions, and reduced burning contributed to the expansion of woody plants and declining nitrogen availability in our five study ecosystems. Shrub biomass in particular was consistently one of the strongest predictors of ecosystem change, equaling or exceeding the effects of other biotic and abiotic factors. In contrast, there was relatively little evidence for mega-herbivore control on plant community composition and nitrogen availability. The ability of plants to determine the fate of terrestrial ecosystems during periods of global environmental change may therefore be greater than previously thought.

The Aghnadarragh site presents the most complete known Midlandian (last cold stage) sequence in Ireland. Above a glacial till and below organic deposits of the Aghnadarragh Interstadial, a unit of poorly sorted gravel and diamicton yielded numerous fossils of woolly mammoth and rarer musk ox, the first record of that species in Ireland. The mammoth molars are of relatively small size and distinctive morphology that probably relate to local environmental conditions. Dating of three mammoth molars by Electron-Spin-Resonance indicates an age for the faunal horizon in the range 109 to 74 ka, corresponding to the later part of MIS 5, presumably MIS 5d or 5b in view of the cold-adapted flora and fauna, or possibly early MIS 4. This in turn suggests that the underlying glacigenic deposits, assigned to the Fermanagh Stadial, formed during a cold stage preceding the last interglacial, rather than being early Midlandian in age as generally assumed. Copyright © 2015 John Wiley & Sons, Ltd.

Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0–2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths.

House mice from 24 Scottish and Faroese islands show positive correlation of skeletal size with island area, conforming to a model of resource limitation in very small islands. Molar size is not correlated with island size, suggesting greater genetic canalization; smaller individuals have larger tooth to body size ratio. The size variation may have a simple genetic basis or may be ecophenotypic. The offset between skeletal and molar size has potential use in the fossil record as a marker for these rapid effects, while longer-term evolutionary change reverts to approximate tooth—body size isometry. Collation of related studies indicates frequently deterministic relationships of small-mammal body size to island size. The parameters of the relationship (positive, negative or parabolic) vary widely with case study according to biotic and abiotic factors. In the present study there was no relationship of mouse size to any variable (e.g. presence of competitors) except island area.

The largest antlers of any known deer species belonged to the extinct giant deerMegaloceros giganteus. It has been argued that their antlers were too large for use in fighting, instead being used only in ritualized displays to attract mates. Here, we used finite-element analysis to test whether the antlers ofM. giganteuscould have withstood forces generated during fighting. We compared the mechanical performance of antlers inM. giganteuswith three extant deer species: red deer (Cervus elaphus), fallow deer (Dama dama) and elk (Alces alces). Von Mises stress results suggest thatM. giganteuswas capable of withstanding some fighting loads, provided that their antlers interlocked proximally, and that their antlers were best adapted for withstanding loads from twisting rather than pushing actions, as are other deer with palmate antlers. We conclude that fighting inM. giganteuswas probably more constrained and predictable than in extant deer.

There has been much discussion of the role of behaviour in evolution, especially its potential to lead morphological evolution by placing the organism in a novel selective environment. Many adaptations of living species can be imagined to have originated in this way, although documented examples are relatively few. A fruitful arena for testing hypotheses about behavioural innovation is the fossil record. Traditionally, the behaviour of fossil species has been deduced from their morphology, precluding the observation of a behavioural lead preceding morphological evolution. This circularity can be broken by examining behavioural proxies independent of the adaptive morphology itself. Examples applicable to fossil remains include dietary information (e.g. wear traces on teeth, stable isotopes) and trace fossils indicating locomotor mode (footprints). The signature of a behavioural lead would be an observed shift in behaviour from one horizon (or taxon) to another, followed later by a functionally-related morphological change. This pattern can be sought either in finely-stratified anagenetic sequences of fossils (stratophenetic approach) or among fossils with well-resolved species-level phylogenies (cladistic approach). An array of case studies from the literature is presented. These include feeding shifts in finely-resolved sequences of vertebrates ranging from freshwater fish to terrestrial ungulates, as well as locomotor changes crucial to major evolutionary transitions in the origin of tetrapods, birds, and humans. The latter examples highlight the role of behaviour in initiating exaptation (the requisitioning of structure for a new function). The case studies also illustrate the challenges of using fossil sequences to elucidate behavioural roles, including insufficient stratigraphic resolution and uncertainty over the adaptive function of observed traits. By the same token, they suggest criteria for choosing promising cases for research, as well as for formulating testable hypotheses about evolutionary modes. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112, 315–331.

The fossil record richly illustrates the origin of morphological adaptation through time. However, our understanding of the selective forces responsible in a given case, and the role of behaviour in the process, is hindered by assumptions of synchrony between environmental change, behavioural innovation and morphological response. Here I show, from independent proxy data through a 20-million-year sequence of fossil proboscideans in East Africa, that changes in environment, diet and morphology are often significantly offset chronologically, allowing dissection of the roles of behaviour and different selective drivers. These findings point the way to hypothesis-driven testing of the interplay between habitat change, behaviour and morphological adaptation with the use of independent proxies in the fossil record.

The current paucity of Pleistocene vertebrate records from the Arabian Peninsula – a landmass of over 3 million km 2 – is a significant gap in our knowledge of the Quaternary. Such data are critical lines of contextual evidence for considering animal and hominin dispersals between Africa and Eurasia generally, and hominin palaeoecology in the Pleistocene landscapes of the Arabian interior specifically. Here, we describe an important contribution to the record and report stratigraphically-constrained fossils of mammals, birds and reptiles from recent excavations at Ti’s al Ghadah in the southwestern Nefud Desert. Combined U-series and ESR analyses of Oryx sp. teeth indicate that the assemblage is Middle Pleistocene in age and dates to ca. 500 ka. The identified fauna is a biogeographical admixture that consists of likely endemics and taxa of African and Eurasian affinity and includes extinct and extant (or related Pleistocene forms of) mammals ( Palaeoloxodon cf. recki , Panthera cf. gombaszogenis , Equus hemionus , cf. Crocuta crocuta , Vulpes sp., Canis anthus, Oryx sp.), the first Pleistocene records of birds from the Arabian Peninsula ( Struthio sp., Neophron percnopterus , Milvus cf. migrans , Tachybaptus sp. Anas sp., Pterocles orientalis , Motacilla cf. alba ) and reptiles (Varanidae/ Uromastyx sp.). We infer that the assemblage reflects mortality in populations of herbivorous animals and their predators and scavengers that were attracted to freshwater and plant resources in the inter-dune basin. At present, there is no evidence to suggest hominin agency in the accumulation of the bone assemblages. The inferred ecological characteristics of the taxa recovered indicate the presence, at least periodically, of substantial water-bodies and open grassland habitats.

The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming ( Dicrostonyx torquatus ), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity.

The Kostolac mammoth was discovered in 2009 in Pleistocene deposits adjacent to the Drmno open-cast lignite mine in the Serbian Danube Basin. On the basis of cranial and dental features, the individual is identified as the so-called ‘steppe’ mammoth, Mammuthus trogontherii. The remains are those of an old male of estimated age around 62 years, and comprise one of the most complete and best-preserved known skeletons of this species, and the first from the region. Skeletal height is estimated as around four metres, and body mass 9.5 t. The excellent preservation of the skeleton provides new information about the osteology of M. trogontherii, an evolutionary intermediate between the better-known ancestral mammoth Mammuthus meridionalis and woolly mammoth Mammuthus primigenius. The find is also remarkable for the articulated condition of the skeleton, the animal occupying a crouching posture which is probably little-altered from its original death position. This and the depositional environment of the skeleton, a broad, fast-flowing river, suggest that the animal died in relatively shallow water and was very rapidly buried in river sediments. Based on the known European record of typical (large-sized) M. trogontherii of this kind, the age of the Kostolac skeleton and its enclosing sediments is between 1.0 and 0.4 Ma.

The last glaciation was a dynamic period with strong impact on the demography of many species and populations. In recent years, mitochondrial DNA sequences retrieved from radiocarbon-dated remains have provided novel insights into the history of Late Pleistocene populations. However, genotyping of loci from the nuclear genome may provide enhanced resolution of population-level changes. Here, we use four autosomal microsatellite DNA markers to investigate the demographic history of woolly mammoths (Mammuthus primigenius) in north-eastern Siberia from before 60 000 years ago up until the species' final disappearance c.4000 years ago. We identified two genetic groups, implying a marked temporal genetic differentiation between samples with radiocarbon ages older than 12 thousand radiocarbon years before present (ka) and those younger than 9ka. Simulation-based analysis indicates that this dramatic change in genetic composition, which included a decrease in individual heterozygosity of approximately 30%, was due to a multifold reduction in effective population size. A corresponding reduction in genetic variation was also detected in the mitochondrial DNA, where about 65% of the diversity was lost. We observed no further loss in genetic variation during the Holocene, which suggests a rapid final extinction event.

In 1986 remains of an adult woolly mammoth, Mammuthus primigenius (Blumenbach), were discovered at Norton Farm Pit, Condover, south of Shrewsbury, UK. Preliminary stratigraphical investigations indicated that this individual dated to the Devensian Late-glacial Interstadial, then the first evidence for survival of mammoth in Britain following the Last Glacial Maximum. Initial radiocarbon analysis confirmed this interpretation. Subsequent excavations in 1987/1988 recovered the remains of a further three juvenile mammoth individuals. All of these remains were found in the spoil heaps of overburden (ex situ) and their true stratigraphical context had to be reconstructed from the remnants surviving in the Pit. The 1987/1988 excavations enabled stratigraphical investigation of the site and submission of samples for radiocarbon (14C) dating, including the use of ultrafiltration pretreatment for bone samples, with the aims of reconstructing the geological and palaeoenvironmental evolution of the site and the sedimentary context of the unstratified mammoth remains. These results are presented here. This investigation indicates that the woolly mammoth remains at Condover derive from a dead-ice landscape dominated by eskers, kames and kettle-hole basins, and that the sedimentary sequence in which the mammoth remains were found forms the infilling of a kettle-hole basin. The sedimentary infilling and formation of the kettle-hole basin through ice block melt-induced subsidence were syngenetic. 14C determinations indicate that basin infill was initiated prior to Greenland Interstadial 1, and probably in Greenland Stadial 2 i.e. before 14.7 ka BP and that it continued until the early Holocene, around 8 ka BP. The sedimentological and 14C data indicate that the unstratified mammoth remains can be attributed to a dark grey clayey sandy silt (Unit C1), which accumulated during the earlier part of Greenland Interstadial 1 (14 to 14.5 ka BP) within an actively subsiding slow-flowing, beaded, fluvial network characterized by channels and pools/lakes, and with relatively shallow marginal slopes. The sedimentary architecture indicates survival of the buried ice block into Greenland Interstadial 1 and final melting only towards the end of the Interstadial at ca. 12.65 ka BP. Copyright © 2009 John Wiley & Sons, Ltd.

The Condover mammoths, discovered by chance in 1986, are a remarkably well-preserved assemblage of partial skeletons unique in western and central Europe. The skeletons were preserved in a kettle-hole infill and recovered ex situ, requiring careful anatomical reconstruction. This revealed the skeleton of a 28-year-old adult male woolly mammoth (Mammuthus primigenius), largely complete except for the cranium, the partial skeletons of four or five juveniles in the age range 3–6 years, plus sparse remains of a subadult individual. The adult skeleton bears several traces of pathology, particularly a badly fractured but re-healed scapula. The presence of blowfly puparia within bone cavities, together with other environmental data and a consideration of mammoth biology, allow a detailed reconstruction of the taphonomy of the skeletons, which appear to have become mired within the kettle-hole. The discovery of complete skeletons from a stratified, dated context contributes strong evidence for the survival of mammoths in Britain and western Europe into the Devensian Late-glacial ca. 14.5–14.0 ka cal BP, within Greenland Interstadial 1. Copyright © 2009 John Wiley & Sons, Ltd.

Body size reduction in mammals is usually associated with only moderate brain size reduction, because the brain and sensory organs complete their growth before the rest of the body during ontogeny. On this basis, 'phyletic dwarfs' are predicted to have a greater relative brain size than 'phyletic giants'. However, this trend has been questioned in the special case of dwarfism of mammals on islands. Here we show that the endocranial capacities of extinct dwarf species of hippopotamus from Madagascar are up to 30% smaller than those of a mainland African ancestor scaled to equivalent body mass. These results show that brain size reduction is much greater than predicted from an intraspecific 'late ontogenetic' model of dwarfism in which brain size scales to body size with an exponent of 0.35. The nature of the proportional change or grade shift observed here indicates that selective pressures on brain size are potentially independent of those on body size. This study demonstrates empirically that it is mechanistically possible for dwarf mammals on islands to evolve significantly smaller brains than would be predicted from a model of dwarfing based on the intraspecific scaling of the mainland ancestor. Our findings challenge current understanding of brain-body allometric relationships in mammals and suggest that the process of dwarfism could in principle explain small brain size, a factor relevant to the interpretation of the small-brained hominin found on the Island of Flores, Indonesia.

The last major global revolution of climate was the transition from the last glacial stage to the present interglacial, ca. 25–10 ka. Vegetational belts and mammalian communities underwent major reorganisation. New radiocarbon data show that the complex series of climatic changes affected the ranges of mammalian species dramatically, but in differing ways related to the ecologies of individual species. For species that ultimately went extinct, the reduction in range was a prolonged and geographically complex process taking thousands or tens of thousands of years. Recent genetic studies using ancient DNA show that this process was often accompanied by loss of genetic variation and, presumably, adaptive flexibility. Even so, some species survived for thousands of years in small, terminal refugia before finally becoming extinct – a pattern akin to the ‘extinction lag’ or ‘extinction debt’ posited for endangered modern taxa. Whether refugial species can survive to re-expand into new areas, especially in anthropogenically disturbed environments, is determined by a complex of factors and is not inevitable.

In 1912, palaeontologist Arthur Smith Woodward and amateur antiquarian and solicitor Charles Dawson announced the discovery of a fossil that supposedly provided a link between apes and humans: Eoanthropus dawsoni (Dawson's dawn man). The publication generated huge interest from scientists and the general public. However, ‘Piltdown man's’ initial celebrity has long been overshadowed by its subsequent infamy as one of the most famous scientific frauds in history. Our re-evaluation of the Piltdown fossils using the latest scientific methods (DNA analyses, high-precision measurements, spectroscopy and virtual anthropology) shows that it is highly likely that a single orang-utan specimen and at least two human specimens were used to create the fake fossils. The modus operandi was found consistent throughout the assemblage (specimens are stained brown, loaded with gravel fragments and restored using filling materials), linking all specimens from the Piltdown I and Piltdown II sites to a single forger—Charles Dawson. Whether Dawson acted alone is uncertain, but his hunger for acclaim may have driven him to risk his reputation and misdirect the course of anthropology for decades. The Piltdown hoax stands as a cautionary tale to scientists not to be led by preconceived ideas, but to use scientific integrity and rigour in the face of novel discoveries.

SummaryThe interval since circa 50 Ka has been a period of significant species extinctions among the large mammal fauna. However, the relative roles of an increasing human presence and a synchronous series of complex environmental changes in these extinctions have yet to be fully resolved [1]. Recent analyses of fossil material from Beringia have clarified our understanding of the spatiotemporal pattern of Late Pleistocene extinctions, identifying periods of population turnover well before the last glacial maximum (LGM: circa 21 Ka) or subsequent human expansion [2–4]. To examine the role of pre-LGM population changes in shaping the genetic structure of an extinct species, we analyzed the mitochondrial DNA of woolly mammoths in western Beringia and across its range. We identify genetic signatures of a range expansion of mammoths, from eastern to western Beringia, after the last interglacial (circa 125 Ka), and then an extended period during which demographic inference indicates no population-size increase. The most marked change in diversity at this time is the loss of one of two major mitochondrial lineages.

The giant deer, or 'Irish elk', has featured extensively in debates on adaptation, sexual selection, and extinction. Its huge antlers--the largest of any deer species, living or extinct--formed a focus of much past work. Yet the phylogenetic position of the giant deer has remained an enigma. On the basis of its flattened antlers, the species was previously regarded as closely related to the living fallow deer. Recent morphological studies, however, have challenged that view and placed the giant deer closer to the living red deer or wapiti. Here we present a new phylogenetic analysis encompassing morphological and DNA sequence evidence, and find that both sets of data independently support a sister-group relationship of giant and fallow deer. Our results include the successful extraction and sequencing of DNA from this extinct species, and highlight the value of a joint molecular and morphological approach.

Background Body size variation within clades of mammals is widespread, but the developmental and life-history mechanisms by which this variation is achieved are poorly understood, especially in extinct forms. An illustrative case study is that of the dwarfed morphotypes of Candiacervus from the Pleistocene of Crete versus the giant deer Megaloceros giganteus, both in a clade together with Dama dama among extant species. Histological analyses of long bones and teeth in a phylogenetic context have been shown to provide reliable estimates of growth and life history patterns in extant and extinct mammals. Results Similarity of bone tissue types across the eight species examined indicates a comparable mode of growth in deer, with long bones mainly possessing primary plexiform fibrolamellar bone. Low absolute growth rates characterize dwarf Candiacervus sp. II and C. ropalophorus compared to Megaloceros giganteus displaying high rates, whereas Dama dama is characterized by intermediate to low growth rates. The lowest recorded rates are those of the Miocene small stem cervid Procervulus praelucidus. Skeletal maturity estimates indicate late attainment in sampled Candiacervus and Procervulus praelucidus. Tooth cementum analysis of first molars of two senile Megaloceros giganteus specimens revealed ages of 16 and 19 years whereas two old dwarf Candiacervus specimens gave ages of 12 and 18 years. Conclusions There is a rich histological record of growth across deer species recorded in long bones and teeth, which can be used to understand ontogenetic patterns within species and phylogenetic ones across species. Growth rates sensu Sander & Tückmantel plotted against the anteroposterior bone diameter as a proxy for body mass indicate three groups: one with high growth rates including Megaloceros, Cervus, Alces, and Dama; an intermediate group with Capreolus and Muntiacus; and a group showing low growth rates, including dwarf Candiacervus and Procervulus. Dwarf Candiacervus, in an allometric context, show an extended lifespan compared to other deer of similar body size such as Mazama which has a maximum longevity of 12 years in the wild. Comparison with other clades of mammals reveals that changes in size and life history in evolution have occurred in parallel, with various modes of skeletal tissue modification. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0295-3) contains supplementary material, which is available to authorized users.

The mammoth lineage provides an example of rapid adaptive evolution in response to the changing environments of the Pleistocene. Using well-dated samples from across the mammoth's Eurasian range, we document geographical and chronological variation in adaptive morphology. This work illustrates an incremental (if mosaic) evolutionary sequence but also reveals a complex interplay of local morphological innovation, migration, and extirpation in the origin and evolution of a mammalian species. In particular, northeastern Siberia is identified as an area of successive allopatric innovations that apparently spread to Europe, where they contributed to a complex pattern of stasis, replacement, and transformation.

The African and Asian elephants and the mammoth diverged ca. 4-6 million years ago and their phylogenetic relationship has been controversial. Morphological studies have suggested a mammoth Asian elephant relationship, while molecular studies have produced conflicting results. We obtained cytochrome b sequences of up to 545 base pairs from five mammoths, 14 Asian and eight African elephants. A high degree of polymorphism is detected within species. With a dugong sequence used as the outgroup, parsimony and maximum-likelihood analyses support a mammoth African elephant clade. As the dugong is a very distant outgroup, we employ likelihood analysis to root the tree with a molecular clock, and use bootstrap and Bayesian analyses to quantify the relative support for different topologies. The analyses support the mammoth African elephant relationship, although other trees cannot be rejected. Ancestral polymorphisms may have resulted in gene trees differing from the species phylogeny Examination of morphological data, especially from primitive fossil members, indicates that some supposed synapomorphies between the mammoth and Asian elephant are variable, others convergent or autapomorphous. A mammoth African elephant relationship is not excluded. Our results highlight the need, in both morphological and molecular phylogenetics, for multiple markers and close attention to within-taxon variation and outgroup selection.

The understanding of Earth's biodiversity depends critically on the accurate identification and nomenclature of species. Many species were described centuries ago, and in a surprising number of cases their nomenclature or type material remain unclear or inconsistent. A prime example is provided by Elephas maximus, one of the most iconic and well-known mammalian species, described and named by Linnaeus (1758) and today designating the Asian elephant. We used morphological, ancient DNA (aDNA), and high-throughput ancient proteomic analyses to demonstrate that a widely discussed syntype specimen of E.maximus, a complete foetus preserved in ethanol, is actually an African elephant, genus Loxodonta. We further discovered that an additional E.maximus syntype, mentioned in a description by John Ray (1693) cited by Linnaeus, has been preserved as an almost complete skeleton at the Natural History Museum of the University of Florence. Having confirmed its identity as an Asian elephant through both morphological and ancient DNA analyses, we designate this specimen as the lectotype of E.maximus. The mass spectrometry proteomics data have been deposited in the ProteomeXchange Consortium with the data set identifier PXD000423. AuthorCount:18

Aim Small body size in Madagascar’s dwarf and mouse lemurs (Cheirogalei-dae) is generally viewed as primitive. We investigated the evolution of bodysize in this family and in its sister-taxon, the Lepilemuridae, from phylogenetic,ontogenetic and adaptive perspectives.Location Madagascar.Methods We used a phylogenetic method to reconstruct the evolution ofbody size in lemurs, and allometric regression models of gestation periods andstatic and growth allometries in Cheirogaleidae and Lepilemuridae to test thehypothesis that dwarfing occurred as a result of truncated ontogeny (progene-sis). We also examined adaptive hypotheses relating body size to environmentalvariability, life history, seasonality of reproduction, hypothermy (use of tor-por), and a diet rich in plant exudates.Results Our results indicated that cheirogaleids experienced at least four inde-pendent events of body size reduction from an ancestor as large as livingLepilemuridae, by means of progenesis. Our interpretation is supported by thepaedomorphic appearance and parallel ontogenetic trajectories of the dwarftaxa, as well as their very short gestation periods and increased fecundity.Lepilemur species that occupy more predictable environments are significantlylarger than those occupying unpredictable habitats.Main conclusions Cheirogaleidae appear to be paedomorphic dwarfs, a con-sequence of progenesis, probably as an adaptation to high environmentalunpredictability. Although the capacity to use hypothermy is related to smallbody size, this advantage is unlikely to have driven dwarfing in cheirogaleids.We propose that gummmivory/exudativory co-evolved with body size reduc-tion in this clade, probably from a folivorous ancestor. Their small size isderived, and their suitability as models for the ‘ancestral primate’ is thereforedubious.KeywordsAncestor reconstruction, body size evolution, dwarfism, hypervariability,island rule, lemurs, Lepilemuridae, Madagascar, ontogeny, progenesis.INTRODUCTIONThe currently popular model of a small, nocturnal primateancestor was largely inspired by an extant family of Malagasylemurs, the Cheirogaleidae, which includes the smallest livingprimates (30–400 g). Mouse lemurs (Microcebus spp.), inparticular, are believed to have retained a series of primitivecharacters associated with their very small size (30–100 g):nocturnality, insectivorous/omnivorous diet, fast life history,nest-building, altricial infants carried by mouth, solitarysocial structure, and a promiscuous mating system (Charles-Dominique & Martin, 1970; Cartmill, 1972, 1974, 1992;Martin, 1972, 1990; Kappeler, 1998; Wimmer et al., 2002;Gebo, 2004; Scheumann & Zimmermann, 2008; Montgomeryet al., 2010; but see Soligo, 2006; Masters et al., 2007; Soligo& Martin, 2007). This interpretation is frequently associated

Human colonization of the New World is generally believed to have entailed migrations from Siberia across the Bering isthmus. However, the limited archaeological record of these migrations means that details of the timing, cause and rate remain cryptic. Here, we have used a combination of ancient DNA, 14C dating, hydrogen and oxygen isotopes, and collagen sequencing to explore the colonization history of one of the few other large mammals to have successfully migrated into the Americas at this time: the North American elk ( Cervus elaphus canadensis ), also known as wapiti. We identify a long-term occupation of northeast Siberia, far beyond the species’s current Old World distribution. Migration into North America occurred at the end of the last glaciation, while the northeast Siberian source population became extinct only within the last 500 years. This finding is congruent with a similar proposed delay in human colonization, inferred from modern human mitochondrial DNA, and suggestions that the Bering isthmus was not traversable during parts of the Late Pleistocene. Our data imply a fundamental constraint in crossing Beringia, placing limits on the age and mode of human settlement in the Americas, and further establish the utility of ancient DNA in palaeontological investigations of species histories.