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Creators/Authors contains: "Stevens, Nancy J"

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  1. Amid global challenges like climate change, extinctions, and disease epidemics, science and society require nuanced, international solutions that are grounded in robust, interdisciplinary perspectives and datasets that span deep time. Natural history collections, from modern biological specimens to the archaeological and fossil records, are crucial tools for understanding cultural and biological processes that shape our modern world. At the same time, natural history collections in low and middle-income countries are at-risk and underresourced, imperiling efforts to build the infrastructure and scientific capacity necessary to tackle critical challenges. The case of Mongolia exemplifies the unique challenges of preserving natural history collections in a country with limited financial resources under the thumb of scientific colonialism. Specifically, the lack of biorepository infrastructure throughout Mongolia stymies efforts to study or respond to large-scale environmental changes of the modern era. Investment in museum capacity and training to develop locally-accessible collections that characterize natural communities over time and space must be a key priority for a future where understanding climate scenarios, predicting, and responding to zoonotic disease, making informed conservation choices, or adapting to agricultural challenges, will be all but impossible without relevant and accessible collections. 
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    Free, publicly-accessible full text available February 11, 2026
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    The fossil record of macroscelidean mammals is notoriously patchy, with a significant spatial and temporal gap separating faunas from the early Oligocene localities of northern Africa and the early Miocene localities of eastern and southern Africa. Here we describe fossil macroscelideans representing Myohyracinae and Rhynchocyoninae recovered from a rift-fill sequence of richly fossiliferous sandstones in the late Oligocene Nsungwe Formation in the Rukwa Rift Basin of southwestern Tanzania. Radiometrically dated to 25.2 Ma, a new Palaeogene myohyracine taxon (Rukwasengi butleri) is represented by a partial maxilla (RRBP 05409) preserving a lightly worn M2-M3. The M2 exhibits a less hypsodont and mesiodistally elongate morphology than the early Miocene Myohyrax oswaldi, and the three-rooted M3 exhibits a tiny mesially positioned fossette. A new rhynchocyonine (Oligorhynchocyon songwensis) is represented by specimens more brachyodont than the early Miocene Miorhynchocyon. Taken together these finds document a rare window into macroscelidean evolutionary history with diversification of the group near the Palaeogene-Neogene Transition (PNT). Continued exploration offers a refined perspective on mid-Cenozoic faunal and ecosystem dynamics on continental Africa, expanding opportunities for recognising trends in palaeobiological diversity across habitat types and through time. 
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  5. The assembly of Africa’s iconic C4grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C4grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C4biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C4grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C4grass–dominated habitats in Africa—and globally—by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution. 
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