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On September 18, 1996, Grand Staircase-Escalante National Monument (GSENM) became the first national monument managed by the US Bureau of Land Management (BLM) and one of the first to protect a landscape based partly on its opportunity for scientific discovery. Its creation was a watershed moment in public land management, because to meet the mandates for its first monument, BLM opted to implement unprecedented support of resource investigations for numerous natural and cultural sciences, including establishing its first ever in-house paleontological field program. The rationale for this was taken directly from the establishing presidential proclamation (6920) which called out GSENM’s untapped paleontological treasure trove as “world-class.” The proclamation also singled out the Late Cretaceous vertebrate fossil record of the Kaiparowits Plateau, largely known at the time through the pioneering work of Drs. Jeff Eaton and Rich Cifelli, who had spent years teasing out the mammalian evolutionary story preserved within. Their work on Mesozoic mammals, alongside sporadic work by other institutions (mainly the University of Utah and Brigham Young University) in the 1970s and 1980s, demonstrated that the Kaiparowits Plateau also held a substantial macrovertebrate record that included beautifully preserved dinosaur skeletons. However, a lack of coordinated effort and the difficult nature of fieldwork in the rugged badlands led to what can only be described as desultory results. The leverage that came with monument status, including logistical and financial support provided by BLM, made this resource more accessible to the paleontological community, stimulating a sudden burst of new field research and discovery. Initial, coordinated, and collaborative fossil inventories started in 2000 by joint BLM, Utah Museum of Natural History, Museum of Northern Arizona, and Utah Geological Survey teams led to a cascade of discoveries, including sites preserving plants, invertebrates, trace fossils, microvertebrates, and macrovertebrates, contextualized by new geological insights. Many of these new fossil finds represent species entirely new to science, with some sites preserving intact snapshots of Late Cretaceous ecosystems that are unmatched globally. Unique geologic conditions resulted in spectacular preservation, sometimes even including soft tissue traces. This renaissance in North American Late Cretaceous paleontology would not have been possible without the focused resources and effort facilitated by the creation of GSENM and the subsequent prioritization of inventory and basic research in its mission. In addition to the science, the public benefits of these efforts have been immense, providing opportunities for direct involvement in the scientific process through volunteer programs, training for several generations of future paleontologists and geologists, innumerable educational programs, and exposure in national and international media outlets through articles, television, and interviews. The collaborative and far-reaching paleontological effort at GSENM has highlighted an often overlooked aspect of public lands management: the importance of US public lands for scientific discovery and education. 

Abstract The Campanian Two Medicine Formation of northwestern Montana, USA, is richly fossiliferous, and discoveries made within the unit over the past century have greatly advanced our appreciation of dinosaur paleobiology and evolution. Previously undifferentiated from a lithostratigraphic perspective, the formation is now subdivided into four new members that include (from base to top) (1) the Rock City Member, (2) the Shields Crossing Member, (3) the Hagans Crossing Member, and (4) the Flag Butte Member. These new formal units and their associated fossil occurrences are also now included in an age model founded on eight high-resolution chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb ages. New age data confirm that the Two Medicine Formation accumulated during much of the Campanian, with deposition spanning ca. 82.4 Ma to 74.4 Ma. New age data further indicate that a major reorganization of depositional systems, marked by a shift from predominantly lacustrine to alluvial facies and accompanied by a dramatic increase in accommodation, transpired near the base of the new Flag Butte Member at ca. 76.3 Ma. This change in depositional regime correlates in age with the Judith River–Belly River discontinuity, which marks the contact between the McClelland Ferry and Coal Ridge Members in the Judith River Formation and coincides with the onset of the Bearpaw transgression in north-central Montana. The new lithostratigraphic and chronostratigraphic framework for the Two Medicine Formation serves to contextualize and calibrate the formation’s rich dinosaur fossil record, which can now be interrogated with increased clarity and precision. These results also provide ground truth for numerical models that explore the structure of the fossil record in relation to alluvial architecture and terrestrial sequence stratigraphy. 

Similar to cellulose synthases (CESAs), cellulose synthase–like D (CSLD) proteins synthesize β-1,4-glucan in plants. CSLDs are important for tip growth and cytokinesis, but it was unknown whether they form membrane complexes in vivo or produce microfibrillar cellulose. We produced viable CESA-deficient mutants of the mossPhyscomitrium patensto investigate CSLD function without interfering CESA activity. Microscopy and spectroscopy showed that CESA-deficient mutants synthesize cellulose microfibrils that are indistinguishable from those in vascular plants. Correspondingly, freeze-fracture electron microscopy revealed rosette-shaped particle assemblies in the plasma membrane that are indistinguishable from CESA-containing rosette cellulose synthesis complexes (CSCs). Our data show that proteins other than CESAs, most likely CSLDs, produce cellulose microfibrils inP. patensprotonemal filaments. The data suggest that the specialized roles of CSLDs in cytokinesis and tip growth are based on differential expression and different interactions with microtubules and possibly Ca²⁺, rather than structural differences in the microfibrils they produce. 

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.