The presence of at least two contemporaneous Pleistocene mastodon taxa in North America (Mammut americanum and M. pacificus) invites re-examination of specimens at the geographic margins of each species in order to determine range boundaries, overlaps, and fluctuations. Third molars from Oregon in the United States, as well as from Hidalgo and Jalisco in Mexico, were found to be morphologically consistent with M. pacificus. Washington in the United States includes a number of specimens that could not be confidently assigned to either taxon. Alberta in Canada was found to have some specimens that were consistent with M. pacificus, but others that were identified as M. americanum. The Alberta specimen referred to M. pacificus is the same tooth found to have a Pliocene divergence time from M. americanum based on mitochondrial genome data from a previous study, suggesting a deep divergence time between the two taxa. The apparent presence of both mastodon taxa in close geographic proximity has interesting paleobiogeographic implications. It is not yet clear if both taxa were present simultaneously in a given location; if not, it suggests fluctuating ranges that may reflect shifting climates and/or biomes over time. Alternatively, if both taxa were simultaneously present in the same place, it may suggest a high degree of niche partitioning in mammutids. Additional accurately dated specimens will be required to resolve this question.

The remains of several 8800 year old structures and associated hearths/roasting features were recently discovered along the trailing edge of the White Sands gypsum dune field in southern New Mexico on the White Sands Missile Range. Formed of anhydrite (burned gypsum), these had been exposed by erosion and in some instances form pedestals above the surrounding ground surface. Found with the features were chipped and groundstone tools, some of the latter likely elements of site furniture, along with debris from artifact use and resharpening. The activities at the site, designated Gypsum Overlook (LA 199959), appear to have taken place at brief, possibly seasonal, intervals and focused on the extraction and processing of plant resources in the eastern Tularosa Basin. Gypsum Overlook provides evidence of a rare Early Holocene site and activities and the earliest dated structures associated with hearth/roasting features currently known from the American Southwest.

Ancient DNA has been useful in reconciling deep evolutionary relationships and responses to ecological changes in proboscideans. Here, we report the sequencing of a mitochondrial genome from a morphologically distinct Pacific mastodon, as well as from six eastern American mastodons with ages that range through the Middle and Late Pleistocene. We show that Pacific mastodons fall within a deeply divergent mitochondrial clade, extending the range of this species into western Canada and potentially Mexico. We also present evidence for at least three discrete expansion events into northeastern coastal regions and identify two new mastodon clades, which contain temporally distinct but geographically colocalized specimens. We integrate these findings with those of previous work into a comprehensive model of Mammut phylogeography.

Late Pleistocene Clovis fluted points and stone flake tools have been found in association with bison at several archaeological sites in western North America. To gain insight into how these tools may have functioned in bison butchery, as well as to assess the assumptions or interpretations of these implements by archaeologists, we conducted a bison-processing experiment. We examined the relative efficacy in the butchering process of hafted fluted points versus handheld flakes and of different Clovis point forms; the types of tool breakage that might occur during butchering; cut-marks that might occur on bones; and, the effects of edge resharpening, both in terms of cutting efficiency and in the before/after form of the points and flake tools used in the process. We also recorded several unanticipated observations on, but not limited to, field-processor injury, the function of fluted point proximal-lateral edge grinding, and tool loss during the butchery event. Overall, our experiment emphasizes the prevalence of equifinality in archaeological interpretation, as it shows that numerous aspects of the Clovis archaeological record – as it is currently understood – can be equally explained by several distinct processes.

Recent ancient DNA work has shed some light on the responses of mastodons to Pleistocene glacial/interglacial cycling but focused primarily on their expansion into Beringia. However, genetics has complicated our understanding of the relationships within Mammut, specifically between Pacific and American mastodon phylogeography and questioned whether these are in fact two separate species or regionally localized morphotypes. Here we expand on both avenues by sequencing and contextualizing the mitochondrial genome of a Pacific mastodon, as well as from several North American eastern specimens throughout the last 800 thousand years. We show that Pacific mastodons fall within a previously established, and deeply divergent mitochondrial clade, extending the range of this species into western Canada and potentially Mexico. We also present evidence for at least three discrete expansion events into northeastern coastal regions (i.e. Nova Scotia and the eastern continental shelf), and identify two new mastodon clades, which contain temporally distinct, but geographically co-occurrent specimens. This work sheds further light on mastodon taxonomy and phylogeography across North America throughout the Pleistocene, highlighting interglacial range expansion into northeastern America mirroring the effects on the western side of the continent (Beringia). ### Competing Interest Statement The authors have declared no competing interest.

Palaeogenetics offers a powerful method to examine the evolutionary relationships between and within taxonomic groups. With sufficient data these analyses can be extended to provide information about the palaeodemography of extinct species. Recent mitochondrial genomes from North American Mammut have highlighted the roles glacial/interglacial cycles had on their range dynamics, but were geographically limited to a subset of American mastodon populations. Here we expand upon previous mastodon ancient DNA research with two new mitochondrial genomes from the American Falls Reservoir in Idaho. Our phylogenetic analyses place mastodons from this region as close relatives of other interglacial mastodons from eastern Beringia and may represent a southward dispersal in response to glacial advance. We attempt to contextualize our findings within the currently known distribution of American and Pacific mastodons, and suggest that a much more comprehensive examination of morphological variation within Mammut is likely required.

which, following Aldenderfer (2006), we define as locations at elevations greater than 2,500 meters above sea level (e.g.,

which, following Aldenderfer (2006), we define as locations at elevations greater than 2,500 meters above sea level (e.g.,

Strontium (Sr) isotope tracers are useful for understanding provenance and mobility in biological materials across multiple disciplines. However, the impact of these techniques is highly dependent on the construction of appropriate comparative baselines (i.e., an isoscape). We present the results of a systematic survey of 87Sr/86Sr values from grasses in the North American Midcontinent with a particular emphasis on sedimentary systems. Although 87Sr/86Sr values are highly variable across the region, the Sr isoscape shows multi-scalar patterns that are dependent on local-to-regional trends in surficial geology. High values are found in bedrock-dominated areas such as the Black Hills (SD) and Ozark Uplift (MO), or formerly glaciated areas where surface deposits are dominated by ice-transported Precambrian clasts. The lowest values are found in river valleys that incorporate eroded Neogene sediments into terrace formation. Intermediate values are found in upland loess and alluvial deposits which blanket much of the study area. We demonstrate trends in large-scale variability of the Midcontinent's 87Sr/86Sr isoscape and suggest that future refinement focus on sub-regional trends in Sr isotope variability.

In 1932, the University of Nebraska State Museum undertook excavations at the Scottsbluff Bison Quarry in northwest Nebraska. Our reanalysis of the extant faunal collection found a minimum of 26 bison present, some with evidence of limited filleting and limb dismemberment. However, we also see signs of post-depositional alteration of the site assemblage and collection bias on the part of the original excavators, and argue that the existing museum collection does not accurately reflect the size and composition of the original bonebed. Skeletal element frequency patterning and variability in stable isotope values suggest severe post-depositional modification, likely fluvial sorting, strongly affected the composition of the bonebed. Despite the site's historical importance, Scottsbluff faunal data should only be used in the future with great caution.

Recent butchery experiments have acknowledged the potential influence of experience level on experimental results. This paper evaluates the effect of skill level on the number and distribution of cut marks produced on fish bone during butchery. Participants of varying skill levels (novice, intermediate, and professional) butchered a total of 30 salmon. Professional butchers differed from intermediate- and novice-level butchers in the number of cut marks produced and the amount of time required to butcher the fish. Specifically, the professional butchers produced nearly 50% fewer cut marks than novices and intermediate-level butchers; the intermediate- and novice-level butchers were statistically indistinguishable. The distribution of the cut marks varied both within and between the skill levels. These results have implications for experimental methodology and for future efforts to identify butchery skill within the archaeological record.

Willis et al. (2008) demonstrated that butchering fish can result in upwards of 500 cut marks per fish skeleton. However, despite various ethnographic studies that describe fish butchering techniques for consumption and drying, cut marks are rarely observed or described for fish bone from archaeological sites. To test the discrepancy between the experimental results and archaeological observations, we buried 13 butchered fish skeletons for 27 months to observe whether the cut marks are still visible after exposure to post-depositional taphonomic processes. After burial, we observed a general decrease – up to 76%, depending on the species of fish – in the number of cut marks visible on fish bone, accompanied by a shift from cut marks on identifiable elements to cut marks on unidentifiable bones and bone fragments. These results impact the methods for analyzing archaeological fish bone, and contribute to our understanding and interpretation of taphonomy, aquatic faunal assemblages, and prehistoric butchering practices.

Sediment consolidation can influence both stone flake artifact inclination and vertical displacement. In this paper we present a novel experiment for investigating the effect of sediment consolidation on the morphology of stone flakes. Focusing specifically on the variables of gravel size and pressure, we show that sediment consolidation does not appear to result in the creation of retouched assemblages from nonretouched ones. Bend-break fractures via sediment consolidation did occur at higher frequencies, and as such the occurrence of bend-breaks needs further experimentation to tease out other specific contexts in which they occur. Overall, however, our experimental results suggest that in most cases archaeologists should not be concerned with sediment consolidation altering the appearance of flaked stone assemblages. Sediment consolidation can influence both stone flake artifact inclination and vertical displacement. In this paper we present a novel experiment for investigating the effect of sediment consolidation on the morphology of stone flakes. Focusing specifically on the variables of gravel size and pressure, we show that sediment consolidation does not appear to result in the creation of retouched assemblages from nonretouched ones. Bend-break fractures via sediment consolidation did occur at higher frequencies, and as such the occurrence of bend-breaks needs further experimentation to tease out other specific contexts in which they occur. Overall, however, our experimental results suggest that in most cases archaeologists should not be concerned with sediment consolidation altering the appearance of flaked stone assemblages. Sediment consolidation can influence both stone flake artifact inclination and vertical displacement. In this paper we present a novel experiment for investigating the effect of sediment consolidation on the morphology of stone flakes. Focusing specifically on the variables of gravel size and pressure, we show that sediment consolidation does not appear to result in the creation of retouched assemblages from nonretouched ones. Bend-break fractures via sediment consolidation did occur at higher frequencies, and as such the occurrence of bend-breaks needs further experimentation to tease out other specific contexts in which they occur. Overall, however, our experimental results suggest that in most cases archaeologists should not be concerned with sediment consolidation altering the appearance of flaked stone assemblages.

Analysis of the faunal remains recovered from two penecontemporaneous Early Holocene archeological sites on the Clary Ranch in western Nebraska offers a series of functional insights on the organizational structure of Late Paleo-Indian subsistence behavior on the central Great Plains of North America. At each location, radiocarbon assays on charcoal and bone indicate occupation between 9100 and 9000 BP. The deposits appear to represent functionally divergent, although complementary, dimensions of a single, spatially differentiated settlement and subsistence system situated along a intermittent tributary of the North Platte River. The Clary Ranch site provides a view from the perspective of a late summer–early fall secondary processing area for bison carcasses derived from a nearby mass kill. The intensive character of carcass exploitation here, involving defleshing and marrow extraction, suggests that the bulk of the yield was destined for storage in anticipation of impending winter food shortages. The primary component at the partially excavated, stratified O.V. Clary site is a residential camp, with evidence for occupation during the mid-summer, mid-winter, and late winter/early spring. On-site activities there are organized around an intact hearth area, to which the carcass parts from at least six bison were transported for processing and subsequent consumption. Non-bison remains recovered from the hearth area include coyote, box turtle, raven, great horned owl, and several small, indeterminate passerines