Southeastern Montana Research Articles

Imperiled wanderlust lichens in steppe habitats of western North America comprise geographically structured mycobiont lineages and a reversal to sexual reproduction within this asexual clade

The northern North American Cordillera is a globally significant center of endemism. In western North America, imperiled arid steppe habitats support a number of unique species, including several endemic lichens. However, processes driving diversification and endemism in this region remain unclear. In this study, we investigate diversity and phylogeography of the threatened wanderlust lichens (mycobiont = Rhizoplaca species) which occur unattached on calcareous soils in steppe habitats. Wanderlust lichens comprise three species of lichen-forming fungi (LFF) – Rhizoplaca arbuscula, R. haydenii, and R. idahoensis (endangered, IUCN Red List) – which occur in fragmented populations in Idaho and Wyoming, with more limited populations in southern Montana and northern Utah. These lichens reproduce almost exclusively via large, asexual vegetative propagules. Here, our aims were to (i) assess the evolutionary origin of this group and identify phylogeographic structure, (ii) infer ancestral geographic distributions for lineages within this clade, and (iii) use species distribution modeling to better understand the distribution of contemporary populations. Using a genome-skimming approach, we generated a 19.1Mb alignment, spanning ca. half of the complete LFF genome, from specimens collected throughout the entire range of wanderlust lichens. Based on this phylogeny, we investigated phylogeographic patterns using RASP. Finally, we used MaxEnt to estimate species distribution models for R. arbuscula and R. haydenii. We inferred a highly structured topology, with clades corresponding to distinct geographic regions and morphologies collected throughout the group’s distribution. We found that R. robusta, a sexually reproducing taxon, is clearly nested within the vagrant Rhizoplaca clade. Phylogeographic analyses suggest that both dispersal and vicariance played significant roles throughout the evolutionary history of the vagrant Rhizoplaca clade, with most of the dispersal events originating from the Salmon Basin in eastern Idaho – the center of diversity for this group. Despite the fact that wanderlust lichens are dispersal limited due to large, unspecialized vegetative propagules, we inferred multiple dispersal events crossing the Continental Divide. Comparing herbarium records with species distribution models suggests that wanderlust lichens don’t fully occupy the areas of highest distribution probability. In fact, documented records often occur in areas predicted to be only marginally suitable. These data suggest a potential mismatch between contemporary habitats outside of the center of diversity in eastern Idaho with the most suitable habitat, adding to the vulnerability of this imperiled complex of endemic lichens.

Ecogeomorphic interactions of Russian olives (Elaeagnus angustifolia) and point‐bar morphology along Powder River, Montana, USA

AbstractPoint bars are crucial alluvial features that help sustain meandering river ecosystems. They are influenced by interactions among physical processes and biological components, such as riparian vegetation. Understanding the mechanisms underlying these interactions can inform management decisions. The meandering Powder River in southeastern Montana, USA, provides a valuable study system for fluvial interactions because it has no major human alterations. Riparian stands of non‐native Russian olive trees (Elaeagnus angustifolia) became noticeable after ~50‐year flood in 1978. Fortuitously, 20 channel cross‐sections had been established in 1975 and 1977 and have been surveyed periodically ever since. This temporally extensive dataset was coupled with a spatially extensive dataset of 85 point‐bar cross‐sections derived from high‐resolution LiDAR that enabled evaluation of interactions between Russian olives and point‐bar morphology through time and space. Based on published literature and field observations, we hypothesised that an increase in the width of Russian olive stands would result in (1) a decrease in the overall point‐bar slope, (2) an increase in point‐bar heights and (3) in point‐bar toe‐slopes. The results indicated that point‐bar slopes did decrease with an increase in stand width, supporting the first hypothesis (R2 = 0.87). However, point‐bar heights decreased with an increase in stand width (R2 = 0.63), contradicting the second hypothesis and there was no relation between point‐bar toe‐slopes and stand width (R2 < 0.1). The reverse hypothesis that point‐bar morphology controls Russian olive stand widths makes more biophysical sense. Thus, Russian olive stand width increases as the point‐bar slope and height decrease (R2 = 0.79 and 0.50), which provide a greater area of inundation for colonisation. This study demonstrates that geomorphology is controlling non‐native vegetation colonisation along Powder River, but that the subsequent stabilisation associated with Russian oliveexpansion may in turn upset the critical geomorphic balance between bank erosion and point‐bar aggradation necessary for a stable meandering system.

The Paleocene Horse Creek florule, Tongue River Member of the Fort Union Formation, southeastern Montana, USA

We investigated leaf, cone and fruit impressions preserved in a siltstone deposit between coal seams in the late Paleocene Tongue River Member near Otter, southeast Montana, to assess the floristic diversity and composition. We document the presence of Taxodium based on seed cone scales as well as foliage branches and associated pollen cones, and a low-diversity angiosperm assemblage of about 15 genera dominated by Platanaceae (Platanus, Macginitiea, Macginistemon) and Cornales (Cornus, Davidia, Amersinia, Browniea), cf. Trochodendraceae (Zizyphoides, Nordenskioeldia), augmented by Aesculus, Trochodendroides, Ulmites and Porosia. Most of these genera were widespread in the Paleocene of the Northern Hemisphere. The low diversity of this florule is consistent with that of Tiffanian assemblages elsewhere in Montana and Wyoming. The leaf known as Phyllites demoresii Brown is proposed as a likely candidate to correspond with the extinct fruits called Porosia verrucosa (Lesquereux) Hickey emend. Manchester et Kodrul.

Fire and Nitrogen Effects on Aristida purpurea Mineral Concentrations

Purple threeawn (Aristida purpurea Nutt.) is a perennial bunchgrass indigenous to much of North America that often dominates disturbed or previously overgrazed rangelands and is mostly avoided by herbivores as forage. Management of threeawn using fire and nitrogen addition can increase its forage quality and likelihood of selection by livestock. We assessed effects of fire, nitrogen fertilizer addition, and phenological stage on purple threeawn mineral concentrations the first growing season postfire on two similar sites in southeastern Montana. Fire (no fire, summer fire, fall fire) and rate of nitrogen fertilizer addition (0, 46, 80 kg N·ha−1) were arranged in a completely randomized, fully factorial design. Samples were collected at five phenological stages throughout each growing season. Minerals were evaluated using laboratory analysis of potassium (K), calcium (Ca), phosphorus (P), sulfur (S), magnesium (Mg), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) concentrations. With no nitrogen addition, summer and fall fire increased Ca from 0.22% to 0.38% and 0.31%, respectively, S from 0.08% to 0.15% and 0.13%, and Mg from 0.06% to 0.14% and 0.12%, while fall fire decreased Fe from 289 to 176 ppm. In the vegetative stage, fire (fall and summer averaged) increased K from 0.38% to 1.08%, Ca from 0.22% to 0.35%, P from 0.10% to 0.23%, S from 0.08% to 0.16%, Mg from 0.05% to 0.13%, Zn from 19.2 ppm to 35.8 ppm and Cu from 2.8 ppm to 6.2 ppm. Increasing rate of nitrogen addition and advancing phenological stage had little to no effect on mineral concentrations relative to fire effects. Results indicate prescribed fire can increase mineral concentrations from deficient levels to exceeding requirements for growing cattle, providing more evidence supporting use of prescribed fire to increase forage quality and potential herbivore utilization of purple threeawn within 1 yr following fire.

The effects of discharge and bank orientation on the annual riverbank erosion along Powder River in Montana, USA

Annual bank erosion was measured at multiple cross sections along the free-flowing meandering Powder River in the western United States from 1979 through 2019. Bank erosion was separated into two components—above water and underwater erosion. Above water erosion was measured as the annual bank retreat rate (0–15.4 m y−1). Underwater erosion rate (0–47 m3 m−1 y−1) was calculated as the volume eroded below the water level corresponding to the dominant annual peak discharge, Qp. This paper focuses primarily on the underwater erosion. A total of 491 annual erosion rates were calculated for 23 bank sites along a 90-km study reach in southeastern Montana. Sites were not just hotspots for bank erosion but represent the spectra of variables such as the radius of curvature divided by channel width, R/w (2–86), the peak discharge, Qp (22.7–314 m3 s−1), and the bank orientation (0–360°).Local annual bank erosion was extremely variable in time and space. It was episodic and unsynchronized along the study reach with the maximum annual bank erosion occurring in different years at different bank sites. The composite probability distribution of all 491 annual bank erosion rates was best modeled by a zero-adjusted Weibull distribution. Individual probability distributions for each of the 23 sites were all different from each other and from the composite distribution highlighting the extreme variability. The correlation of the annual underwater erosion with channel geometry and bank variables was low (R2 < 0.31) but the correlation was higher for peak discharge with 25% of the sites having R2 > 0.50.Time-averaging reduced the variability at each site and when grouped into five peak-discharge classes each class was correlated with R/w as a power law with an exponent of about −1. Reach-averaging also reduced the variability for each year, and when grouped by bank orientation (north-, east-, south-, and west-facing), bank erosion was linearly related to Qp with south- and west-facing orientations having about twice as much erosion per unit discharge (0.030 m3 m−1 y−1/m3 s−1) than north- and east-facing orientations.Bank erosion was found to be not just a multi-variate complex process with little correlation and high variability that suggests randomness, but also a process that was a function of a different combinations of variables at different sites at the same time. However, this high variability was reduced by time- and reach-averaging, which produced predictable results analogous to the central limit theorem.

The mid-Paleocene fruit and seed flora from the Fort Union Formation of Newell’s Nook, southeastern Montana, USA

The middle Paleocene Newell’s Nook biota of the Tongue River Member of the Fort Union Formation, southeastern Montana, is best known for its early Tiffanian mammalian fauna. Here, we describe an informative fruit and seed assemblage from this locality. These records refine the lower stratigraphic boundary for several plant genera known more widely from the Fort Union paleobotanical localities of less certain stratigraphic assignment within the upper Paleocene and help to fill a gap in our knowledge about the mid-Paleocene floristic composition of the Rocky Mountain and Great Plains region. Recognized plant taxa belong to the families Characeae, Taxaceae, Menispermaceae, Sabiaceae, Hamamelidaceae, Cercidiphyllaceae, Vitaceae, Cucurbitaceae and Juglandaceae. Several morphotypes remain uncertain as to familial position. Based on the dispersal syndromes of extant relatives, about 2/3 of these fruits were adaptive for animal dispersal, with hard seeds or endocarps covered by a fleshy outer layer. Dry seeds and nuts were likely part of the diet of small mammals. The Newell’s Nook locality presents another rare example of a North American Paleocene fruit and seed locality and provides insights to the dietary habits and ecology of the co-occurring fauna of this time.

Great Plains Population of the Dwarf Shrew (Sorex nanus), with a Record from Nebraska

A diminutive shrew from Sioux County, Nebraska, is shown to be the first state record for the dwarf shrew, Sorex nanus. This specimen appears to be a member of a dwarf shrew population occurring on the Great Plains in the vicinity of the Black Hills in western South Dakota, eastern Wyoming, and southeastern Montana, but not within the Black Hills proper. Other populations of this species occur in montane environments in the Rocky Mountains, from Montana south through Wyoming, Colorado, New Mexico, Utah, and some isolated mountains in Arizona. The arid grassland habitats inhabited by the Great Plains population are strikingly different from the alpine and subalpine rockslides, coniferous forests, montane streams, and sagebrush communities at elevations generally above 1400 m occupied by other populations. Future researchers should examine genetic and ecological relationships among these populations of the dwarf shrew.

Reservoir characterization and production history matching of Lower Cretaceous, Muddy Formation in Ranch Creek area, Bell Creek oil field, Southeastern Montana, USA

A detailed reservoir description of the Lower Cretaceous, Muddy Formation is an essential step for developing an enhanced oil recovery project in the Bell Creek field. The applied workflow highlighted the role of key uncertainties that were not well addressed during early field development. Several challenges including: stratigraphic subdivision of the reservoir units, rock type complexity due to diagenesis, petrophysical data inconsistencies and fluid contacts have historically led to hurdles in reservoir development. The study outlines a workflow used to refine some of these uncertainties and generate better inputs for the geologic model. The Ranch Creek area at Bell Creek field in southeastern Montana is characterized by a clastic sequence of mixed rock types from argillaceous mudstone, bioturbated tightly cemented to clean sandstone lithofacies. Delta front to fluvial-dominated depositional settings as well as diagenesis played an important role in controlling reservoir quality and geometry. The facies complexity is reflected in rock properties controlling fluid migration through the reservoir intervals. The lithofacies types are clustered into three groups, each with characteristic porosity and permeability cutoffs based on core plugs measurements. The rock types are linked to depositional facies obtained from the petrographic description and calibrated to the clusters derived from the capillary pressure measurements. Porosity distribution within the reservoir is biased to the diagenetic complexity and rock type distribution. Three different transforms were used to calculate the corresponding permeability to the modeled porosity parameter. Modeling water saturation for the three different capillary pressure groups using the J-function approach improves the spatial distribution of water saturation and leads to a better match of historical oil and water production rates.Reservoir simulation is crucial to improve our understanding of rock and fluid properties. Integrating dynamic data such as pressure, production and injection rates helps to reduce the uncertainty of the model parameters. The history match process highlights the need to tune the output of the static model. Iterations on the static model, focused on changing the ranges of key parameters such as facies volume fractions and water saturation that contain the most uncertainties. Applying these changes results in an improved geological model that provides a better data to the simulation model. The tuned static model was able to reproduce the observed results. Matching the pressure data supports a valid oil-in-place which is consistence with historical volumetric calculation.

Our Relationship to Water and Experience of Water Insecurity among Apsáalooke (Crow Indian) People, Montana.

Affordable access to safe drinking water is essential to community health, yet there is limited understanding of water insecurity among Native Americans. Therefore, the focus of this paper is to describe Apsáalooke (Crow Indian) tribal members’ experiences with water insecurity. For Apsáalooke people, local rivers and springs are still vitally important for traditional cultural activities. We interviewed 30 Native American adults living on the Crow Reservation in Southeastern Montana. Participants answered six open-ended interview questions about their water access, costs of obtaining water and changes in their domestic and traditional water uses. Participants emphasized how the use of water has changed over time and described the complex challenges associated with addressing water insecurity in their community, including the importance of considering the spiritual and cultural impacts of water insecurity on health. Water insecurity is a growing global problem and more attention and efforts are needed to find appropriate and affordable solutions.

Impacts of Coal Resource Development on Surface Water Quality in a Multi‐jurisdictional Watershed in the Western United States

AbstractThis study focuses on water quality and quantity impacts from natural resource development on watersheds originating on Crow tribal lands in southeastern Montana. Field research analysis will focus on the surface water quality in three adjacent watersheds. This study will determine impacts to water quality from reclaimed coal mine spoils surface runoff and produced water discharge from coal bed methane wells within the watersheds. A secondary research objective is to determine a baseline assessment of surface water in watersheds prior to proposed mine development, particularly on tribally owned and allotted tracts. Historical data from state agencies will also be compared to data collected within watersheds on tribal lands. Water quality impacts from mining development may be more pronounced than that of coal bed methane as the reclaimed mining sites have demonstrated lasting impacts on the nearby surface water quality in the study area. Historical and current samples have demonstrated increased sodium absorption ratio and sodium levels downstream of a mine site in a tributary to the primary watershed. A sample from a pond in another reclaimed mine site contained the highest sodium adsorption ratio levels of all surface water samples. Coal bed methane development impacts may have been transient in the primary watershed surface water based on sample results. Historical oil and gas development appears to be impacting surface water quality within the southernmost watershed. Analysis has shown the increasing degradation of water quality in watersheds downstream and across the state boundary of Montana into Wyoming where natural resource development has occurred.

Dynamic relations for the deposition of sediment on floodplains and point bars of a freely-meandering river

Fluvial features such as floodplains and point bars are built by sediment deposition and sculpted by erosion. Long-term measurements (38 yr) of the cross-section topography of active floodplains and point bars along the freely-meandering Powder River in southeastern Montana, USA (mean daily discharge of 12.5 m3 s−1), were used to develop dynamic relations between annual sediment deposition and peak-flood discharge. Five floodplain sections and five point-bar sections were selected from 24 cross sections along a 90-km study reach. At each cross section the sediment deposition volume per unit streamwise distance was computed as the difference between two topographic surveys made in consecutive years.Snowmelt floods were found to be the dominant annual process. However, other processes such as flash floods, ice breakup floods, and autumnal floods were important episodically. The dynamic relations were linear for both fluvial features. The snowmelt deposition-discharge relations showed, in general, that point bars were about two times more efficient at trapping sediment than floodplains. Each relation had a discharge threshold that must be exceeded before sediment was deposited. Although these discharge thresholds for floodplains and point bars had essentially the same mean value (69 and 71 m3 s−1, respectively), they represented different processes. Thresholds for other rivers will probably differ from those for Powder River because of different channel geometry and sediment characteristics.

Goshen Points in the Northwestern Plains: New Evidence from Montana

ABSTRACTGoshen projectile points are commonly associated with the regions of eastern Wyoming, western South Dakota, and southeastern Montana; however, they have also been identified as isolates and in a few sites in northern Colorado and the Canadian Prairie Provinces. This paper shares an occurrence of an atypical Goshen point made on a flake from southwestern Montana.

Morning Star Rises: Peace, Power, and Righteousness in the Face of Colonization

Morning Star RisesPeace, Power, and Righteousness in the Face of Colonization Leo Killsback (bio) Morning Star was the first chief of whom I learned as a child. My mother told me that we were direct descendants of a man of considerable stature who led his people to the homeland that we lived on, the Northern Cheyenne Indian Reservation in southeastern Montana. As a child I struggled to understand the traditional concept of a chief, since many of my perceptions of Indians were dictated by the void of Indians in American culture. I, like most children then and now, was fascinated with our people's military culture, which highlighted the feats of historic figures and modern veterans of war. I was not interested in the peace and patience demanded of true leaders, who were burdened with the difficult tasks of decision making, peace making, and uniting people to achieve common goals. I did not realize how difficult it is to lead, especially when it comes to uniting groups of people who may differ in various cultural ways. It is equally and sometimes more difficult to lead people who may share common histories, languages, and cultures. In such cases, divisions may exist based on petty differences, like opinions, agendas, and even personalities. Like most Indigenous communities, the older people typically held positions of leadership, in particular, the older and wiser men. But the true leaders, those who led without positions or validation, seemed to always be older and wiser women. One of the major challenges in Indian Country is leadership. Currently, it seems that most American Indians still hold military [End Page 5] veterans in high regard as political leaders. Meanwhile, intellectual Indians, college-educated Indians, remain a threat to most people because they represent the oppressive establishment created by the reservation system and the assimilation policies of the U.S. government. The likelihood of this dynamic to change is inevitable and becomes more apparent as more American Indians pursue and attain college degrees, especially those who are able to confront and disrupt the oppressive reservation system. Currently, American Indians do not necessarily have a strong understanding of "good leadership" in governance because we rely on modern colonial perspectives, which define leaders as elected officials and leadership from positions or titles. Historically, we relied on traditional concepts, and Indian leaders did not acquire their positions through status, fame, or fortune. Rather, they gained their prestige by keeping the best interests of their people in mind and by their devotion to preserving their cultures, especially during unforeseen times of hardship. My goal for this article is to reexamine the legacy of a nineteenth-century Cheyenne leader named Vóóhéhéve (Morning Star) who has been both vilified and romanticized in non-Indian scholarly and popular accounts. His story represents the struggle for American Indian legitimacy as he represents both realism and fantasy in America's history. In various eras in America's written history, Morning Star, his name, and his story have been viciously attacked, demonized, fictionalized, fabricated, and eventually praised and glamorized. Most Indian chiefs are treated the same in written history, but always by authors who knew little or nothing about these leaders or their families. We have only begun to respect the voices of American Indians. An American Indian scholar who was familiar with the Lakota side of Morning Star's family was Charles Eastman, Ohiyesa. He described Morning Star, known as Dull Knife to the Lakota, as follows: The life of Dull Knife, the Cheyenne, is a true hero tale. Simple, childlike yet manful, and devoid of selfish aims, or love of gain, he is a pattern for heroes of any race. Dull Knife was a chief of the old school. Among all the Indians of the plains, nothing counts save proven worth. A man's caliber is measured by his courage, unselfishness and intelligence. Many writers confuse history with fiction, but in Indian history their women and old men and even children witness the main events, and not being absorbed in daily papers and magazines, these events are rehearsed over and over with few variations. Though orally preserved, their accounts are therefore accurate. But they have...

Measuring succession: methods for establishing long-term vegetation monitoring sites

Successional stages are often characterized by dominant plant species (species with the highest cover) and their effect on the structure and function of an area through time. However, the plant species determining the ecosystem properties and plant community dynamics may not be the dominant, especially when it is exotic. Understanding plant community dynamics in ecosystems that are uncharacterized and/or affected by invasive plant species requires a data-driven approach and proper placement of monitoring plots. To generate robust datasets on vegetation change through time, monitoring plot placement must consider the scale of ecological variation for both vegetation and soils and plots would ideally be replicated within similar ecological site types to quantify the consistency of successional transitions. We characterized soil and vegetation across and within seven floodplains affected by Russian olive (Elaeagnus angustifolia L.) along the Yellowstone River in southeastern Montana, USA. Using modern Classification and Regression Trees (CART) and multivariate net differentiation, we identified five distinct plant community types, or classes, characterized by their tertiary woody plant cover, not the primary species, Russian olive. Our findings indicate that Russian olive communities differ across space, and these riparian areas can be classified into distinct plant community types. Characterizing plant community types via this analytical approach should allow practitioners to modify management decisions and forecast succession within relevant plant communities.

Design and Implementation of a Scalable, Automated, Semi-permanent Seismic Array for Detecting CO2 Extent During Geologic CO2 Injection

A proof-of-concept demonstration using a scalable, automated, semipermanent, seismic array (SASSA) is being conducted to test a novel seismic method for detecting and tracking an injected CO2 plume as it traverses discreet points within a reservoir in southeastern Montana at Bell Creek oil field which is undergoing commercial CO2 enhanced oil recovery (EOR). This document serves to describe the technical design of the project infrastructure, the operational approach, corresponding data collection, and data-processing activities.

Monitoring 3.2 Million Tonnes of CO2 at the Bell Creek Oil Field

A research-monitoring program is being conducted at the Bell Creek oil field by the Plains CO2 Reduction Partnership, led by the Energy & Environmental Research Center, to evaluate and demonstrate the cost-effectiveness of strategies for monitoring CO2 storage associated with a commercial enhanced oil recovery (EOR) project. The Bell Creek oil field, operated by Denbury Onshore LLC as a commercial EOR project, is an oil-bearing, Lower Cretaceous sandstone reservoir located in southeastern Montana, USA. CO2 injection for commercial EOR began in May 2013 and has resulted in over 3.2 million tonnes of associated CO2 storage as of July 2016.

Artists' Depictions of Catsteps in the Loess Hills of Iowa: Evidence for Mid-Nineteenth Century Climate Change

Catsteps (also known as terracettes) are the staircase-like features common on hillslopes of the Loess Hills of western Iowa. The record of artistic depictions of the Loess Hills was examined to determine when catsteps appeared. Landscape artists George Catlin and Karl Bodmer traveled up the Missouri River in 1832 and 1833, respectively, and between them, produced 30 works of art depicting either the Loess Hills or the loess bluffs on the Nebraska side of the river. Only one painting by Bodmer of Blackbird Hill on the Nebraska side possibly shows catsteps. Moreover, an engraving based on the painting and another painting of the same site by Bodmer do not show catsteps. The Assistant State Geologist, Orestes St. John, produced five sketches of the Loess Hills in 1868, three of which show well-defined catsteps. The appearance of catsteps during the period 1833-1868 may be related to the appearance of gullies during the period 1860-1900. An examination of census data shows that intensive grazing of the Loess Hills did not begin until about 1900 so that climate change is a more likely explanation for the appearance of both catsteps and gullies. Since catsteps are more common on the south- and west-facing slopes, which will dry most quickly, the most probable climate change is a decrease in the periodicity of precipitation cycles. Such a climate change is consistent with tree ring data from eastern South Dakota and eastern Montana, but not central and eastern Iowa.

New cranial material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of southeastern Montana, U.S.A.

ABSTRACTPlastomenidae is a speciose clade of soft-shelled turtles (Trionychidae) known from Campanian to Eocene deposits throughout western North America. We here describe two large skulls from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of Carter County, Montana, that document the adult morphology of the plastomenid Gilmoremys lancensis. Whereas juveniles of this species, as previously documented by five subadult skulls, have narrow skulls, a narrow processus trochlearis oticum, a deep and narrow median palatal groove, low accessory ridges, and a secondary palate fully formed by the maxilla, skeletally mature individuals have notably broad skulls, a broad processus trochlearis oticum, a shallow but broad median palatal groove, high accessory ridges, and a substantial contribution of the vomer to the secondary palate. An expanded phylogenetic analysis reveals that the Campanian Aspideretoides foveatus and the Paleocene Aspideretoides superstes, nov. comb., are situated within Plastomenidae as sister to all previously identified plastomenid turtles, despite their general resemblance to trionychine soft-shelled turtles. The name Aspideretoides should therefore not be used as a taxonomic wastebasket for fossil trionychids with unclear phylogenetic relationships.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Joyce, W. G., T. R. Lyson, and S. Williams. 2016. New cranial material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of southeastern Montana, U.S.A. Journal of Vertebrate Paleontology, e1225748. DOI: 10.1080/02724634.2016.1225748.

Use of least-cost path analysis to identify potential movement corridors of swift foxes in Montana

The swift fox ( Vulpes velox ) is a small grassland canid native to the North American Great Plains. A reintroduced swift fox population in Canada and northern Montana appears to be isolated from those existing in the central and southern Great Plains. We developed a swift fox habitat suitability model for southeastern Montana, the region between the 2 populations. The resulting model indicated that 67.9% of the study area consisted of highly suitable habitat. We conducted a least-cost path analysis to evaluate the connectivity of swift fox habitat in the study area to existing swift fox populations in the region. We identified a potential dispersal corridor through southeastern Montana that could facilitate movement between swift fox populations in northern Montana and northern Wyoming and identified 4 prairie dog complexes in Rosebud, Custer, and Powder River Counties, Montana, that could serve as potential swift fox reintroduction sites. Each site comprised several prairie dog colonies in close proximity and encompassed ≥ 95 km2. We evaluated the effect that swift fox populations established in each potential reintroduction site could have on population connectivity. Our results as well as future surveys could inform swift fox management and reintroduction programs in Montana.

Coal aquifer contribution to streams in the Powder River Basin, Montana

Groundwater contributions to streams can be reduced by groundwater withdrawal associated with coalbed methane and coal mine production. Quantifying the groundwater contribution to streams aids the assessment of potential impacts to in-stream flow and provides information necessary for energy producers to use coproduced water for beneficial purposes, rather than treating it as a waste product. Stream flow, field parameters, common ions, and isotopes of carbon and strontium were measured on Otter Creek and the Powder River in southeastern Montana. Direct streamflow measurements were ineffective because of the magnitude and nature of coalbed contribution. The coal groundwater contribution did not exceed the geochemical detection threshold on two nearby streams. Geochemical models based on isotopic data proved to be the most effective analytical method, resulting in baseflow measurements from coal aquifers of 28–275 l s−1.