http://hdl.handle.net/10453/35355 2026-10-15T03:47:48Z http://hdl.handle.net/10453/197049 Title: A dataset of radiocarbon dates from Holarctic mammal collagen purified with high-quality chemistry. Authors: Herrando-Pérez, S; Mitchell, KJ; Southon, JR; Turney, CSM; Stafford, TW Abstract: Radiocarbon dates from megafaunal remains provide insights into climatic and anthropogenic factors shaping past ecosystems. Chronologies have advanced through rigorous chemical purification (pretreatment) of fossil vertebrate collagen for accelerator mass spectrometry (AMS) radiocarbon dating. We present MEGA14C, a comprehensive dataset of late Quaternary AMS radiocarbon dates for Holarctic large-bodied mammals, based on collagen purified by ultrafiltration (92% of records), XAD-2 purification (7%) and hydroxyproline isolation (1%). MEGA14C includes 11,715 dates spanning 8 orders, 23 families, 78 genera, 133 species and 18 subspecies, 27% from extinct taxa, and dominated by Equus, Bos, Mammuthus, Rangifer, Bison, Ursus, Cervus, Canis, Coelodonta and Sus. Where available, geolocation, genetic and isotopic data are provided. Pretreatment is critical for accurate and reproducible radiocarbon measurements, yet 44% of published dates lack this information. We addressed this gap through over 10,000 personal communications (out of >100,000 emails) with researchers and AMS laboratories among the parties involved in fossil dating. This unique dataset supports (pre)historical research and provides a foundation for future expansion and/or integration into a global radiocarbon repository. 2026-02-17T00:00:00Z http://hdl.handle.net/10453/195896 Title: Party membership and affiliation: Realizing party linkage and community in the twenty-first century Authors: Gauja, A; Kosiara-Pedersen, K; Weissenbach, K Abstract: Since the turn of the century, the emergence of new (types of) parties and the organizational evolution of established ones has challenged traditional ideas of party membership with innovative forms of membership and affiliation. These shifts affect how parties build linkage and sustain their communities. While many studies focus on the changing nature of membership within individual parties, a comprehensive, comparative understanding of these changes – what is driving them, and how they impact the democratic functioning of political parties – is lacking. We establish a theoretical and empirical framework to investigate these phenomena that distinguishes between the concept of party membership (what it is supposed to achieve) and the way in which party membership is operationalized from the perspective of the state, parties as organizations and individuals. Our framework and illustrative examples serve as a foundation for the comprehensive empirical analysis undertaken by the contributors to this special issue. 2025-03-01T00:00:00Z http://hdl.handle.net/10453/195418 Title: Grand Canyon landslide-dam and paleolake triggered by the Meteor Crater impact at 56 ka Authors: Karlstrom, KE; Baisan, CH; Kring, DA; Hereford, R; Turney, C; Hogg, A; Norman, LM; O’Brien, P; Palmer, JG; Rittenour, TM; Ballensky, J; Crossey, LJ Abstract: This paper hypothesizes that the Meteor Crater impact in Arizona, USA, 56,000 years ago triggered landslides in Grand Canyon that dammed the Colorado River and formed Nan koweap paleolake. This is compatible with shock and earthquake physics for the impact that infer a M5.4 seismic event, attenuated to an effective magnitude of M3.5 at Grand Canyon. Results that support the hypothesis include radiocarbon dating of driftwood and lumines cence dating of associated slack-water lake sediments that are preserved in caves up to 60 m above the modern Colorado River. Radiocarbon ages from two locations, including Stanton’s Cave, date the driftwood as 55.25 ± 2.44 ka (n = 4). Sediments associated with the driftwood gave a luminescence age of 56.00 ± 6.39 ka (n = 2). These six Grand Canyon dates, and three published ages for the Meteor Crater impact, show statistically indistinguishable results that support the hypothesis for a geologically instantaneous series of events with a mean age of 55.60 ± 1.30 ka. This work highlights the value of radiocarbon dating near the limits of the technique, integration of multiple dating methods, and seismic and landslide hazards associ ated with meteorite impacts in regions of extreme topography like Grand Canyon. 2025-07-15T00:00:00Z http://hdl.handle.net/10453/195417 Title: Development of the Intcal Database Authors: Bronk Ramsey, C; Adolphi, F; Austin, W; Bard, E; Bayliss, A; Blaauw, M; Cheng, H; Edwards, RL; Friedrich, M; Heaton, T; Hogg, A; Hua, Q; Hughen, K; Kromer, B; Manning, S; Muscheler, R; Palmer, J; Pearson, C; Reimer, P; Reimer, R; Richards, D; Scott, M; Southon, J; Turney, C; Wacker, L Abstract: The IntCal family of radiocarbon (14C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the 14C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access database. This has ensured transparency in terms of the data used in the construction of the ratified calibration curves. As the IntCal database expands, work is underway to facilitate best practice for new data submissions, make more of the associated metadata available in a structured form, and help those wishing to process the data with programming languages such as R, Python, and MATLAB. The data and metadata are complex because of the range of different types of archives. A restructured interface, based on the "IntChron"open-access data model, includes tools which allow the data to be plotted and compared without the need for export. The intention is to include complementary information which can be used alongside the main 14C series to provide new insights into the global carbon cycle, as well as facilitating access to the data for other research applications. Overall, this work aims to streamline the generation of new calibration curves. 2025-01-01T00:00:00Z