Pleistocene glacial-interglacial cycles are correlated with dramatic temperature oscillations. Examining how species responded to these natural fluctuations can provide valuable insights into the impacts of present-day anthropogenic climate change. Here we present a phylogeographic study of the extinct American mastodon (Mammut americanum), based on 35 complete mitochondrial genomes. These data reveal the presence of multiple lineages within this species, including two distinct clades from eastern Beringia. Our molecular date estimates suggest that these clades arose at different times, supporting a pattern of repeated northern expansion and local extirpation in response to glacial cycling. Consistent with this hypothesis, we also note lower levels of genetic diversity among northern mastodons than in endemic clades south of the continental ice sheets. The results of our study highlight the complex relationships between population dispersals and climate change, and can provide testable hypotheses for extant species expected to experience substantial biogeographic impacts from rising temperatures.

Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e. hard-object feeding), many primates with similar morphologies consume an array of tough and hard foods—complicating dietary inferences of early hominins. We posit that tapirs, large herbivorous mammals showing variable sagittal crest development across species, are ideal models for examining correlations between textural properties of food and sagittal crest morphology. Here, we integrate dietary data, dental microwear texture analysis, and finite element analysis to clarify the functional significance of the sagittal crest in tapirs. Most notably, pronounced sagittal crests are negatively correlated with hard-object feeding in extant, and several extinct, tapirs and can actually increase stress and strain energy. Collectively, these data suggest that musculature associated with pronounced sagittal crests—and accompanied increases in muscle volume—assists with the processing of tough food items in tapirs and may yield similar benefits in other mammals including early hominins.

Mining processes generate waste rock, tailings, and slag that can increase potentially toxic metal (PTM) concentrations in soils. Un-reclaimed, abandoned mine sites are particularly prone to leaching these contaminants, which may accumulate and pose significant environmental and public health concerns. The characterization and spatial delineation of PTMs in soils is vital for risk assessment and soil reclamation. Bumpus Cove, a once active mining district of eastern Tennessee, is home to at least 47 abandoned, un-reclaimed mines, all permanently closed by the 1950s. This study evaluated soil physicochemical properties, determined the spatial extent of PTMs (Zn, Mn, Cu, Pb, and Cd), and examined the influence of soil properties on PTM distribution in Bumpus Cove, TN. Soil samples (n = 52) were collected from a 0.67 km2 study area containing 6 known abandoned Pb, Zn, and Mn mines at the headwaters of Bumpus Cove Creek. Samples were analyzed for Zn, Mn, Cu, Pb, and Cd by microwave-assisted acid digestion and flame atomic absorption spectrometry (FAAS) (12-1,354 mg/kg Zn, 6-2,574 mg/kg Mn, 1-65 mg/kg Cu, 33-2,271 mg/kg Pb, and 7-40 mg/kg Cd). Of the measured PTMs, only Pb exceeds permissible limits in soils. In addition to the PTM analyses, soil physical (texture, moisture content, and bulk density) and chemical (pH, cation exchange capacity (CEC), and total organic carbon (TOC)) properties were evaluated. Spatially weighted multivariate regression models developed for all PTMs using soil physicochemical properties produced improved results over ordinary least squares (OLS) regression models. Models for Zn (R2 = 0.71) and Pb (R2 = 0.69) retained covariates epH, moisture content, and CEC (Zn), and pH and CEC (Pb). This study will help define PTM concentration and transport and provide a reference for state and local entities responsible for contaminant monitoring in Bumpus Cove, TN.

During the late Pleistocene of North America (≈36,000 to 10,000 years ago), saber-toothed cats, American lions, dire wolves, and coyotes competed for prey resources at Rancho La Brea (RLB). Despite the fact that the giant short-faced bear (Arctodus simus) was the largest land carnivoran present in the fauna, there is no evidence that it competed with these other carnivores for prey at the site. Here, for the first time, we report carious lesions preserved in specimens of A. simus, recovered from RLB. Our results suggest that the population of A. simus from RLB was more omnivorous than the highly carnivorous populations from the Northwest. This dietary variation may be a consequence of different competitive pressures.

Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ∼1.0-2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths.

Elsevier Ltd and INQUA Protocyon troglodytes was a hypercarnivorous South American canid that died out during the Late Pleistocene-early Holocene extinction, an event that eliminated most large mammals on the continent. The precise timing of these extinctions is poorly understood in South America, primarily due to a lack of radiometric dates on taxa. Of the extinct South American canids, P. troglodytes have the most extensive fossil record and widest distribution. However, the age of these specimens is based on relatively coarse association with other dated taxa or sediments. This paper describes an unpublished specimen of P. troglodytes and present the first 14C date and stable isotopes (δ13C and δ15N) for the species. This is the first taxon date for the genus and species, with an age of 17,338 ± 85 BP, and represents the youngest specimen dated by any means. The isotopes indicate that P. troglodytes was a hypercarnivore, in agreement with morphological studies, and that Equus neogeus, Hippidion principale, Stegomastodon platensis, Toxodon, and Megatherium americanum may have been part of its diet.

The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.g., pits and scratches) introduces interobserver error, with higher error being produced by less experienced individuals. Dental microwear texture analysis (DMTA), which analyzes microwear features in three dimensions, alleviates some of the problems surrounding two-dimensional microwear methods by reducing observer bias. Here, we assess the accuracy and comparability within and between 2D and 3D dental microwear analyses in herbivorous and carnivorous mammals at the same magnification. Specifically, we compare observer-generated 2D microwear data from photosimulations of the identical scanned areas of DMTA in extant African bovids and carnivorans using a scanning white light confocal microscope at 100x magnification. Using this magnification, dental microwear features quantified in 2D were able to separate grazing and frugivorous bovids using scratch frequency; however, DMTA variables were better able to discriminate between disparate dietary niches in both carnivorous and herbivorous mammals. Further, results demonstrate significant interobserver differences in 2D microwear data, with the microwear index remaining the least variable between experienced observers, consistent with prior research. Overall, our results highlight the importance of reducing observer error and analyzing dental microwear in three dimensions in order to consistently interpret diets accurately.

Members of the Erycinae are small to medium-sized, semi-fossorial snakes in the family Boidae (Squamata, Serpentes) known today from Africa, southwestern Asia, India, and western North America. Erycines were the predominate snakes in faunas of North America during the Paleogene. In North America, only the minute, extinct erycine Pterygoboa is known to have additional wing-like processes situated on the postzygapophyses of the vertebrae. Here we report on Pterygoboa from one latest Oligocene (25-24 Ma) (White Springs) and two early Miocene (≈20-19 Ma) localities (Miller, Thomas Farm) in Florida. These specimens represent a significant chronological and southern geographic range extension for the genus and permit an amendment to the morphological description of this unusual snake.

South-central Florida's latest Hemphillian Palmetto Fauna includes two machairodontine felids, the lion-sized Machairodus coloradensis and a smaller, jaguar-sized species, initially referred to Megantereon hesperus based on a single, relatively incomplete mandible. This made the latter the oldest record of Megantereon, suggesting a New World origin of the genus. Subsequent workers variously accepted or rejected this identification and biogeographic scenario. Fortunately, new material, which preserves previously unknown characters, is now known for the smaller taxon. The most parsimonious results of a phylogenetic analysis using 37 cranio-mandibular characters from 13 taxa place it in the Smilodontini, like the original study; however, as the sister-taxon to Megantereon and Smilodon. Accordingly, we formally describe Rhizosmilodon fiteae gen. et sp. nov. Rhizosmilodon, Megantereon, and Smilodon (= Smilodontini) share synapomorphies relative to their sister-taxon Machairodontini: serrations smaller and restricted to canines; offset of P3 with P4 and p4 with m1; complete verticalization of mandibular symphysis; m1 shortened and robust with widest point anterior to notch; and extreme posterior "lean" to p3/p4. Rhizosmilodon has small anterior and posterior accessory cusps on p4, a relatively large lower canine, and small, non-procumbent lower incisors; all more primitive states than in Megantereon and Smilodon. The former also differs from Megantereon and Smilodon gracilis by having a very small mandibular flange. Rhizosmilodon is the oldest known member of the Smilodontini, suggesting that the tribe originated in North America. Two more derived, similar-sized species evolved in parallel during the Blancan, Megantereon hesperus and Smilodon gracilis. The former is rarer, known only from the north-central and northwestern US, and presumably dispersed into the Old World. The latter is known from the eastern and southern US, and dispersed into South America.

Warning systems for natural hazards provide notification of potential hazard events through the monitoring of natural processes. Monitoring is usually technological with a wide range of detection and notification hardware available and in use. Warning sources can be natural, informal, or official and if available time to respond is short, natural and informal warnings may be the only source of information before impact of a hazard. In recent years there has been an increasing focus on end-to-end warning systems, which focus heavily on community involvement, preparedness, and warning response actions. Response actions are usually to either evacuate or shelter in place, with the added complexity of sometimes protecting valuables. Decisions to disseminate awarning are often difficult tomake, especially if the desired response is to evacuate, because as certainty of the onset or specifics of a hazard such as location, magnitude, and intensity increases over time the time remaining to respond decreases. The delivery and content of a warning message has been heavily studied and there are a range of characteristics of effective warning messages. Warning systems are often not fully effective, so they should be considered along with a range of risk management options, especially land use planning.