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1. Caught in a bottleneck: Habitat loss for woolly mammoths in central North America and the ice‐free corridor during the last deglaciation

   https://doi.org/10.1111/geb.13238  

   Wang, Yue ; Widga, Chris ; Graham, Russell W. ; McGuire, Jenny L. ; Porter, Warren ; Wårlind, David ; Williams, John W. ; Lyons, ed., Kathleen ( December 2020 , Global Ecology and Biogeography)

   Identifying how climate change, habitat loss, and corridors interact to influence species survival or extinction is critical to understanding macro‐scale biodiversity dynamics under changing environments. In North America, the ice‐free corridor was the only major pathway for northward migration by megafaunal species during the last deglaciation. However, the timing and interplay among the late Quaternary megafaunal extinctions, climate change, habitat structure, and the opening and reforestation of the ice‐free corridor have been unclear.

   North America.

   15–10 ka.

   Woolly mammoth (Mammuthus primigenius).

   For central North America and the ice‐free corridor between 15 and 10 ka, we used a series of models and continental‐scale datasets to reconstruct habitat characteristics and assess habitat suitability. The models and datasets include biophysical and statistical niche models Niche Mapper and Maxent, downscaled climate simulations from CCSM3 SynTraCE, LPJ‐GUESS simulations of net primary productivity (NPP) and woody cover, and woody cover based upon fossil pollen from Neotoma.

   The ice‐free corridor may have been of limited suitability for traversal by mammoths and other grazers due to persistently low productivity by herbaceous plants and quick reforestation after opening 14 ka. Simultaneously, rapid reforestation and decreased forage productivity may have led to declining habitat suitability in central North America. This was possibly amplified by a positive feedback loop driven by reduced herbivory pressures, as mammoth population decline led to the further loss of open habitat.

   Declining habitat availability south of the Laurentide Ice Sheet and limited habitat availability in the ice‐free corridor were contributing factors in North American extinctions of woolly mammoths and other large grazers that likely operated synergistically with anthropogenic pressures. The role of habitat loss and attenuated corridor suitability for the woolly mammoth extinction reinforce the critical importance of protected habitat connectivity during changing climates, particularly for large vertebrates.

    

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2. BITS : A Bayesian Isotope Turnover and Sampling model for strontium isotopes in proboscideans and its potential utility in movement ecology

   https://doi.org/10.1111/2041-210X.14218  

   Yang, Deming ; Bowen, Gabriel J. ; Uno, Kevin T. ; Podkovyroff, Katya ; Carpenter, Nancy A. ; Fernandez, Diego P. ; Cerling, Thure E. ( October 2023 , Methods in Ecology and Evolution)

   Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) of incrementally grown tissues have been widely used to study movement ecology and migration of animals. However, the time scale of⁸⁷Sr/⁸⁶Sr incorporation from the environment into tissue and how it may influence data interpretation are still poorly understood. Using the relocation of a zoo elephant (Loxodonta africana) named Misha, we characterise and model the⁸⁷Sr/⁸⁶Sr turnover process using high‐resolution measurements of its tusk dentine. We seek to develop a framework that can improve quantitative interpretation of⁸⁷Sr/⁸⁶Sr data in tissues.

   The⁸⁷Sr/⁸⁶Sr transition associated with the relocation is measured using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) on a prepared tusk slab. We develop a turnover model (BITS), with a rapidly exchanging central pool and a slowly exchanging peripheral pool, in a Bayesian statistical framework. The measured dentine data are first used to calibrate model parameters. The parameters are then used to estimate possible⁸⁷Sr/⁸⁶Sr input time series from two datasets via model inversion: a fidelity test using Misha's dentine data and a case study using published dentine measurements from an Alaskan Woolly Mammoth (Mammuthus primigenius).

   The LA‐ICP‐MS data are consistent with a two‐compartment turnover process with equivalent half‐lives of 41 days for the central pool and 170 days for the peripheral pool. The model inversion shows good fidelity when estimating the intake⁸⁷Sr/⁸⁶Sr time series associated with Misha's relocation. In the case study, the model suggests an abrupt pattern of change in, and a much wider range of, intake⁸⁷Sr/⁸⁶Sr values than expressed in the woolly mammoth dentine data themselves.

   Our framework bridges the gap between environmental⁸⁷Sr/⁸⁶Sr variation and data measured in tusk dentine or other incrementally grown tissues. It could be coupled with movement models and additional isotope tracers to study seasonal residency or the spatial and temporal patterns of movement/migration. The generic turnover processes can be adapted to other isotope systems, additional incremental tissues, or other organisms, thus expanding our modelling toolkit to investigate niche partitioning, life history traits and behavioural patterns in conservation biology, archaeology and paleoecology.

    

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3. A female woolly mammoth’s lifetime movements end in an ancient Alaskan hunter-gatherer camp

   https://doi.org/10.1126/sciadv.adk0818  

   ROWE, AUDREY ; BATAILLE, CLEMENT ; BALEKA, SINA ; COMBS, EVELYNN ; CRASS, BARBARA ; FISHER, DANIEL ; GHOSH, SAMBIT ; HOLMES, CHARLES ; KRASINSKI, KATHRYN ; LANOË, FRANÇOIS ; et al ( January 2024 , Science)

   Woolly mammoths in mainland Alaska overlapped with the region’s first people for at least a millennium. However, it is unclear how mammoths used the space shared with people. Here, we use detailed isotopic analyses of a female mammoth tusk found in a 14,000-year-old archaeological site to show that she moved ~1000 kilometers from northwestern Canada to inhabit an area with the highest density of early archaeological sites in interior Alaska until her death. DNA from the tusk and other local contemporaneous archaeological mammoth remains revealed that multiple mammoth herds congregated in this region. Early Alaskans seem to have structured their settlements partly based on mammoth prevalence and made use of mammoths for raw materials and likely food. 

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4. Higher than present global mean sea level recorded by an Early Pliocene intertidal unit in Patagonia (Argentina)

   https://doi.org/10.1038/s43247-020-00067-6  

   Rovere, Alessio ; Pappalardo, Marta ; Richiano, Sebastian ; Aguirre, Marina ; Sandstrom, Michael R. ; Hearty, Paul J. ; Austermann, Jacqueline ; Castellanos, Ignacio ; Raymo, Maureen E. ( December 2020 , Communications Earth & Environment)

   Reconstructions of global mean sea level from earlier warm periods in Earth’s history can help constrain future projections of sea level rise. Here we report on the sedimentology and age of a geological unit in central Patagonia, Argentina, that we dated to the Early Pliocene (4.69–5.23 Ma, 2σ) with strontium isotope stratigraphy. The unit was interpreted as representative of an intertidal environment, and its elevation was measured with differential GPS at ca. 36 m above present-day sea level. Considering modern tidal ranges, it was possible to constrain paleo relative sea level within  ±2.7 m (1σ). We use glacial isostatic adjustment models and estimates of vertical land movement to calculate that, when the Camarones intertidal sequence was deposited, global mean sea level was 28.4 ± 11.7 m (1σ) above present. This estimate matches those derived from analogous Early Pliocene sea level proxies in the Mediterranean Sea and South Africa. Evidence from these three locations indicates that Early Pliocene sea level may have exceeded 20m above its present level. Such high global mean sea level values imply an ice-free Greenland, a significant melting of West Antarctica, and a contribution of marine-based sectors of East Antarctica to global mean sea level.

    

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5. Status, kinship, and place of burial at Early Bronze Age Bab adh‐Dhra': A biogeochemical comparison of charnel house human remains

   https://doi.org/10.1002/ajpa.23982  

   Gregoricka, Lesley_A ; Ullinger, Jaime ; Sheridan, Susan_G ( December 2019 , American Journal of Physical Anthropology)

   The Early Bronze Age (EBA; ca. 3,600–2000 BCE) of the southern Levant underwent considerable transformation as agro‐pastoral communities began to utilize their land more intensively, constructing larger, fortified towns prior to site abandonment at the end of the third millennium. At the site of Bab adh‐Dhra' in Jordan, the dead of the Early Bronze (EB) II–III (ca. 3,100–2,500 BCE) period were communally interred within charnel houses, but important disparities between these structures and their contents may be reflective of ownership and use by particular extended kin groups whose activity patterns, subsistence strategies, and even social status may have differed from one another. Subsequently, we hypothesized that differences in mobility and dietary intake may differentiate tomb groups from one another.

   Dental enamel from 31 individuals interred in three different Early Bronze Age charnel houses (A56, A22, A55) at Bab adh‐Dhra', Jordan were analyzed for strontium, oxygen, and carbon isotope values.

   Strontium isotope ratios (range: 0.70793–0.70842) possessed medians that did not differ statistically from one another, but had ranges that exhibited significant differences in variance. Carbon isotope values (= −13.2 ± 0.5‰, 1σ) were not significantly different.

   General similarities in human isotopic signatures between EB II–III charnel houses A22 and A55 suggest that their activities were likely similar to one another and agree with findings from excavated domestic spaces with little archaeological evidence for economic, social, or political differentiation. More variable strontium isotope ratios and lower carbon isotope values from A22 could reflect a greater involvement with pastoralist practices or regional trade, including the consumption of more¹³C‐depleted foods, while those in A55 may have led a more sedentary lifestyle with greater involvement in cultivating orchard crops. All charnel houses contained nonlocal individuals likely originating from other Dead Sea Plain sites with no EB II–III cemeteries of their own, supporting the idea that extended kin groups throughout the region returned to Bab adh‐Dhra' to bury their dead.

    

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