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Hall's Cave, Kerr county, Texas. (a) Picture of the site located at 3008N, 9932W at an elevation of 500 m in an area of modest topographical relief. Mean annual temperature is 18C and mean precipitation is 800 mm (Collins 2004); (b, c) hypothesized trophic relationships between extinct and extant mammal fauna in the community are depicted. The ellipse represents the projected isotopic niche space. Values are approximate; they were taken from the literature and may not be representative of Hall's Cave. Note the large number of grazers present in the pre-extinction panel. Grey text in the 'post-extinction' panel represents taxa extirpated by the LP megafauna extinction. 

Hall's Cave, Kerr county, Texas. (a) Picture of the site located at 3008N, 9932W at an elevation of 500 m in an area of modest topographical relief. Mean annual temperature is 18C and mean precipitation is 800 mm (Collins 2004); (b, c) hypothesized trophic relationships between extinct and extant mammal fauna in the community are depicted. The ellipse represents the projected isotopic niche space. Values are approximate; they were taken from the literature and may not be representative of Hall's Cave. Note the large number of grazers present in the pre-extinction panel. Grey text in the 'post-extinction' panel represents taxa extirpated by the LP megafauna extinction. 

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Recent studies connecting the decline of large predators and consumers with the disintegration of ecosystems often overlook that this natural experiment already occurred. As recently as 14 ka, tens of millions of large-bodied mammals were widespread across the American continents. Within 1000 yr of the arrival of humans, ∼80% were extinct including...

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... we examine the influence of the LP extinction on a mammal community in the southern Great Plains of North America. Our site, Hall's Cave, lies in the center of the Edwards Plateau (Fig. 1), a distinct region of the Texas Hill country dominated by juniper-oak or oak-mesquite savanna with an understory of mid-to short grasslands ). Because of extensive paleontological excavations and comprehensive radiocarbon dating , Cooke et al. 2003, this site has produced an extremely well dated ( 160 AMS radiocar- bon dates) ...
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... the Edward's Plateau supported a diverse mammal assemblage with mammoth, horse, camels and many other megaherbivores, as well as many medium- and small-bodied species that still occur in the region today. The terminal Pleistocene extinction resulted in the loss of 80% of the large-bodied herbivores and 20% of the apex predators in the ecosystem (Fig. 1b). Thus, Hall's Cave pro- vides an unparalleled opportunity to quantitatively examine the influence of the LP megafauna extinction on mammal community structure, and moreover, to potentially disen- tangle the influence of previously recognized fluctuations in late Quaternary climate from biotic interactions such as ...
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... mammal communities are based on Hall's Cave and the 20 nearby fossil sites on the Edward's Plateau of Texas ( Fig. 1; Supplementary material Appendix 1, Table A1). In the Pleistocene, this region supported an open grassland eco- system (Joines 2011). Today, it consists of a juniper-oak/ mesquite-acacia savanna with an understory of short grasses; both rainfall and temperature is intermediate between dry grasslands/savanna eco-regions ( Collins et al. ...
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... camels, etc.), and not through shifts in the minimum size (Fig. 2d). It led to a fundamental restricting of the shape of the BSD from bimodal to flat, and from right, to left skewed (Fig. 2e, Fig. 3). These shifts were correlated with both climate fluctuations and the LP extinction, with an essentially modern BSD established by the Holocene (Fig. 3, Table 1). The shape of the BSD dis- tribution was significantly different at time periods centered on 10.3, 13.8, 15.3-16.5, and 18.8 ka (two-sample K-S tests, p 0.0001; Table 1). This encompassed the terminus of the Younger Dryas cold episode, which was marked by abrupt warming, the onset of the megafauna extinction at 13.8 ka, and the ...
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... anticipated that the loss of apex carnivores would lead to a restructuring of the guild. The modern apex car- nivores in North America (e.g. jaguar, mountain lion, wolf, grizzly bear) were mesocarnivores in the Pleistocene when saber-tooth and scimitar-toothed cats, dire wolves and the short-faced bear dominated the community (Fig. 1). Because apex carnivores are known to be hyper-carnivorous (Van Valkenburg et al. 2004), we expected that they would form (Fig. 2c) coincident with a decrease in the median/mean body mass, neither the minimum nor the maximum body mass changed until 11-12 ka, around the end of the LP extinction event (Fig. 2d). This suggests that ...
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... some changes in the community were clearly the result of the warming climate at the terminal Pleistocene, it is also clear that the loss of 80% of the megaherbivores and 20% of the apex predators (Fig. 1) between 13.8-11.4 ka fundamentally changed the structure of the mammal com- munity at Hall's Cave. In addition to the turnover at 17-18 ka, there is another increase in beta diversity at 12-14 ka coincident with the LP extinction and largely before the YD event (Fig. 2c). This time the increase in beta diversity is accompanied by a ...
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... the community for most of the late Pleistocene record, even during the warming climate associated with the retreat of glaciers in North America (Fig. 4), this abruptly changed with the LP extinction. The proportion of grazers in the system dropped by more than half, with only bison, prong- horn and a few medium-to small-bodied species surviving (Fig. 1). Because large-bodied grazers help maintain grass- lands (Owen-Smith 1987, their absence probably resulted in encroachment of woody vegetation, which may have changed the relative amount of annual C 3 versus C 4 bio- mass production at the site. 14-EV However, we found the opposite: aggregated pairs tended to be more similar in body ...

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... Widespread biodiversity loss is more than species extinction; it also leads to the loss of ecological function, which may be realized at local, regional, or even global scales. Large-bodied wild mammals, in particular, play an important role within ecosystems through the transport of nutrients and biogeochemical cycling, modification of vegetation composition and structure, ecological interactions with other animals, and even feedbacks with climate (3,(17)(18)(19)(20)(21)(22)(23). Hence, there is growing concern that the ongoing loss of large-bodied wild mammals may lead to the unraveling of ecosystems because these complex ecological roles are not generally replicated by domesticated or smaller-bodied animals (1)(2)(3)(4)11). ...
... These materials are all housed at the Texas Memorial Museum (TMM) in Austin, TX. The initial faunal list for Hall's Cave was compiled by Toomey (55); our ongoing efforts over the past 4 y with the unidentified fossil materials and recent ancient DNA analysis of sediment (98) from this site have resulted in additional species being recovered (SI Appendix, Table S1) (20). ...
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... The Pliocene and Pleistocene evolution of large herbivores megafauna, such as proboscideans, edentates, camelids, and horses, sparked the co-evolution of various specialized predators, scavengers, parasites, etc. 10,11 , many of which went extinct along with the megaherbivores at the end of the Pleistocene. In the Americas alone, this was the fate of more than thirty species of mammalian and avian predators and scavengers 12,13 . ...
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The New World Vulture [Coragyps] occidentalis (L. Miller, 1909) is one of many species that were extinct by the end of the Pleistocene. To understand its evolutionary history we sequenced the genome of a 14,000 year old [Coragyps] occidentalis found associated with megaherbivores in the Peruvian Andes. occidentalis has been viewed as the ancestor, or possibly sister, to the extant Black Vulture Coragyps atratus, but genomic data shows occidentalis to be deeply nested within the South American clade of atratus. Coragyps atratus inhabits lowlands, but the fossil record indicates that occidentalis mostly occupied high elevations. Our results suggest that occidentalis evolved from a population of atratus in southwestern South America that colonized the High Andes 300 to 400 kya. The morphological and morphometric differences between occidentalis and atratus may thus be explained by ecological diversification following from the natural selection imposed by this new and extreme, high elevation environment. The sudden evolution of a population with significantly larger body size and different anatomical proportions than atratus thus constitutes an example of punctuated evolution. 14,000 year old DNA reveals the evolutionary dynamics and adaptations of South American vultures.
... Furthermore, the effects of downsizing and coextinctions could be amplified by possible impacts of future climate change on body size that have also been hypothesized to lead to smaller body mass in mammals (for example, Hoy et al. 44 ) and ectotherms 45 . The predicted future decline and extinction of wild mammals described in this study, which is likely underestimated by not including coextinctions, could generate strong ecological and trophic consequences for wilderness areas, comparable to those triggered by past megafaunal extinctions 18,[46][47][48][49] . Moreover, these changes are currently being seen in marine environments, such as the loss of otters in Pacific kelp ecosystems 37,50 . ...
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Diet and body mass are inextricably linked in vertebrates: while herbivores and carnivores have converged on much larger sizes, invertivores and omnivores are, on average, much smaller, leading to a roughly U-shaped relationship between body size and trophic guild. Although this U-shaped trophic-size structure is well documented in extant terrestrial mammals, whether this pattern manifests across diverse vertebrate clades and biomes is unknown. Moreover, emergence of the U-shape over geological time and future persistence are unknown. Here we compiled a comprehensive dataset of diet and body size spanning several vertebrate classes and show that the U-shaped pattern is taxonomically and biogeographically universal in modern vertebrate groups, except for marine mammals and seabirds. We further found that, for terrestrial mammals, this U-shape emerged by the Palaeocene and has thus persisted for at least 66 million years. Yet disruption of this fundamental trophic-size structure in mammals appears likely in the next century, based on projected extinctions. Actions to prevent declines in the largest animals will sustain the functioning of Earth’s wild ecosystems and biomass energy distributions that have persisted through deep time.
... Fossil identifications are the foundation upon which paleoecological analyses are based and often play an important role in evolutionary analyses. As examples, fossil identifications can have substantial impacts on evolutionary and ecological inferences because they can directly affect investigations relating morphological evolution to past environmental changes (e.g., Moroz et al., 2021), investigations on the mechanisms and timing of lineage diversification through time (e.g., Scarpetta, 2020), and investigations on ecosystem changes over time (e.g., Smith et al., 2016). Therefore, the methods by which we identify fossils require detailed study and attention to recognize limits in our abilities to identify fossil material (Bell et al., 2010). ...
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... We included a total of 79 taxa representing the native terrestrial mammalian fauna from the Terminal Pleistocene to the present. The faunal list was based on the study by Smith, Tomé, et al. (2016), with revisions to reflect changes in mammal taxonomy and additional species newly identified from the site (for details, see Supporting Information Appendix; Table S1). Mammals ranging in size from shrew to bison have been recovered directly in the Hall's Cave fossil record; however, inclusion of nearby sites allowed the complete characterization of the local community. ...
... Note that analysis of any single palaeontological site is highly unlikely to include all mammals within a local community because of taphonomic biases, in addition to the reduced likelihood of preservation of the largest mammals owing to lower density on the landscape (see Supporting Information Appendix). Thus, as has been done previously, taxa from other sites were included if either the natal dispersal distance or the average home range overlapped with Hall's Cave (Smith, Tomé, et al., 2016;Toomey, 1994;Toomey et al., 1993). Most fauna were identified to the species level, but this was not always possible. ...
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... Cave deposits have been an important source of information for studying the climate variability and changes in terrestrial ecosystem across the Late Pleistocene-Holocene transition, especially in arid environments (Jass and George, 2010;Smith et al., 2016;Seersholm et al., 2020;Minckley et al., 2021). Cave assemblages provide excellent data for understanding environmental conditions in the large basins that separate formerly glaciated, mesic mountain ranges. ...
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Natural Trap Cave (NTC) is a well-known fossil locality located in Wyoming that contains a discontinuous record of sediments from the early Sangamonian (∼150 ka) to the present and produces a diverse vertebrate assemblage from 2 to 9 and 23–47 cal ka BP. This study examines changes in the rank abundance distribution (RAD) of NTC's large-bodied (>8 kg) vertebrates, to assess the stability of the local ecosystem surrounding the cave across the Late Pleistocene-Holocene transition. RADs were generated based on 2208 skeletal elements from four stratigraphic units, collected by Gilbert and Martin from 1974 to 1979. All bones included in this study had: a north-west grid coordinate, a known depth below the sediment surface, were over 20% complete and taxonomically diagnostic. Isotaphonomy was assessed using multinomial regressions of %MAU against multiple taphonomic variables: size, shape, degree of abrasion and weathering, fracture type, percent complete, original bulk density, and surface area to volume ratio. Changes in RADs were analyzed using rank abundance curves (RACs), Wilcoxon Rank Sums test, and kurtosis. RADs were also fit to a suite of standard ecological models (i.e., geometric, log-series, zero-sum multinomial, & log-normal) using maximum likelihood and the Akaike Information Criterion corrected for small sample size (AICc). The four faunal assemblages show little variation in taphonomic biasing, so any changes in the RADs reflects changes in the ecosystem. The four RACs showed little change in their shape or faunal composition and are dominated by a few abundant taxa, representing an ecosystem that experienced perturbations (i.e., a concave RAC and a kurtosis value > 3). The Wilcoxon Rank Sums test found no statistical difference among the RADs from the lower three stratigraphic units. This means that the abundance structure of the large-bodied vertebrates did not change prior to (35.8–25.3 cal ka BP) or during the Last Glacial Maximum (25.3–17.2 cal ka BP) and the local ecosystem surrounding NTC never approached equilibrium. The uppermost stratigraphic unit represented a mixed Late Pleistocene and Early Holocene assemblage, so changes in ecosystem structure from the Last Glacial Maximum to the Holocene (10.5 cal ka BP – present) cannot be evaluated. Unfortunately, the ecological models used in this study provide little insight into the maturity or processes influencing the formation of the local ecosystem surrounding NTC because only three models produced a ΔAICc value between 4.4 and 6.7.
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... Pleistocene megafauna are thought to have played roles similar to their modern counterparts by maintaining open habitats and enhancing species diversity, repressing fire regimes, and increasing nutrient availability across ecosystems (Johnson, 2009;Rule et al., 2012;Doughty et al., 2013;Ripple et al., 2015;Bakker et al., 2016). In addition to structural changes in vegetation, the extinction likely had cascading effects on community structure and interactions of the surviving mammal species (Smith et al., 2016b;Tóth et al., 2019). ...
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... R. Soc. B 288: 20210121 associations in the past are now significantly disassociated in modern communities [60][61][62][63]. Therefore, our observations of modern communities, and perceptions of specialization across taxa in these environments, may not serve as suitable analogues for past communities. ...
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Palaeoecological interpretations are based on our understanding of dietary and habitat preferences of fossil taxa. While morphology provides approximations of diets, stable isotope proxies provide insights into the realized diets of animals. We present a synthesis of the isotopic ecologies ( δ ¹³ C from tooth enamel) of North American mammalian herbivores since approximately 7 Ma. We ask: (i) do morphological interpretations of dietary behaviour agree with stable isotope proxy data? (ii) are grazing taxa specialists, or is grazing a means to broaden the dietary niche? and (iii) how is dietary niche breadth attained in taxa at the local level? We demonstrate that while brachydont taxa are specialized as browsers, hypsodont taxa often have broader diets that included more browse consumption than previously anticipated. It has long been accepted that morphology imposes limits on the diet; this synthesis supports prior work that herbivores with ‘grazing’ adaptions, such as hypsodont teeth, have the ability to consume grass but are also able to eat other foods. Notably, localized dietary breadth of even generalist taxa can be narrow (approx. 30 to 60% of a taxon's overall breadth). This synthesis demonstrates that ‘grazing-adapted’ taxa are varied in their diets across space and time, and this flexibility may reduce competition among ancient herbivores.
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... A significant emerging threat is also the growing exotic pet trade, and digital platforms in particular are leading to a rapidly growing and easily accessible illegal exotic pet trade online (Siriwat and Nijman, 2018;Siriwat et al., 2019). Although this trade affects numerous small carnivores (Siriwat et al., 2019), it is particularly active for otters (Lutrinae) in Southeast Asia (Gomez and Bouhuys, 2018;Siriwat and Nijman, 2018). ...
... Fourth, the exploitation of small carnivores is likely one of the most difficult threats to address as it has several contributing factors, such as human consumption, commodity trade, and persecution, which incorporate social, economic, and ethical issues. Although 49% of small carnivores are protected by CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), international regulations alone have not halted this pressing threat to small carnivores (Trouwborst, 2015;Siriwat et al., 2019). Given the number of actors, reducing illegal wildlife trade requires a combination of decreasing demand as well as increased regulation, enforcement, and community engagement (Phelps et al., 2016). ...
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Small mammalian carnivores (Carnivora <16 kg) carry out important roles in ecosystems, such as influencing ecosystem structure and providing numerous ecosystem services. Despite their importance, there are contrasting views on the required conservation and management needs for species within this group. In a review of the IUCN Red List species-level assessments, we found that 53 small carnivore species were threatened (CR, EN, or VU) compared to 15 large. However, there were similar proportions of large (4%, 9%) and small (1%, 9%) carnivores endangered with extinction (CR or EN, respectively). We did not find support for small carnivores benefiting from mesopredator release in a global context; more than half of both large and small carnivore species decreasing, suggesting parallel declines. On average, large carnivores received their first IUCN assessment 10 years before small and, since their first assessment, small carnivores have received fewer assessments than large, highlighting the disparity in conservation attention within the guild. The leading threats for all carnivores include biological resource use and land use change. We review the major threats to threatened small carnivores and suggest areas for priority research and conservation. Collectively, we show that small carnivores are as endangered with extinction as are large carnivores, and that small carnivores should be of conservation concern globally, but particularly in species-rich regions of Southeast Asia, sub-Saharan Africa, and Madagascar. To inform conservation, we encourage more research into the basic ecology and demography of small carnivores, particularly regarding current and future threats in the face of global change.
... [86] (terrestrial organisms), [34] (mammals); [96] (mammals) ...
... By the Pleistocene-Holocene transition (11.7 ka), humans had altered the pattern of a preponderance of positive associations (statistically significant rates of coexistence) that had persisted for 300 million years [86]. This shift could not be explained by non-anthropogenic factors (e.g., climate) [86,96]. Application of new methods for differentiating between abiotic and biotic controls on species associations (Table 1) shows that the loss of positive species associations reflects a breakdown in the frequency and importance of biotic interactions [34], such as those between carnivores and their prey [96]. ...
... This shift could not be explained by non-anthropogenic factors (e.g., climate) [86,96]. Application of new methods for differentiating between abiotic and biotic controls on species associations (Table 1) shows that the loss of positive species associations reflects a breakdown in the frequency and importance of biotic interactions [34], such as those between carnivores and their prey [96]. Weakening of biotic interactions may have resulted from the spread of generalist life strategies in the wake of the loss of large-bodied, ecosystem engineering mammals that followed human colonization [34,96]. ...
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Recent renewed interest in using fossil data to understand how biotic interactions have shaped the evolution of life is challenging the widely held assumption that long-term climate changes are the primary drivers of biodiversity change. New approaches go beyond traditional richness and co-occurrence studies to explicitly model biotic interactions using data on fossil and modern biodiversity. Important developments in three primary areas of research include analysis of (i) macroevolutionary rates, (ii) the impacts of and recovery from extinction events, and (iii) how humans (Homo sapiens) affected interactions among non-human species. We present multiple lines of evidence for an important and measurable role of biotic interactions in shaping the evolution of communities and lineages on long timescales.