Late Quaternary Megafaunal Extinctions Research Articles

The timing and ecological consequences of Pleistocene megafaunal decline in the eastern Andes of Colombia

AbstractExamining the ecological consequences of the late Quaternary megafaunal extinctions within biodiversity hotspots is crucial for our understanding of the potential consequences of contemporary extinctions. We present the first multi-species record of spores of coprophilous fungi (SCF) from Monquentiva and the high-Andean forests of Colombia to reconstruct Late Pleistocene and Holocene megafaunal abundance. Fossilised pollen and charcoal are used to examine the consequences of megafaunal declines on the surrounding vegetation and fire activity. Our SCF record indicates the presence of Pleistocene megafauna at least since 30,290 BP, with two waves of megafaunal decline at ca. 22,900 BP and 10,990 BP. At Monquentiva, megafaunal decline in the Early Holocene resulted in transitional non-analogue vegetation, loss of some herbivore-dispersed plant taxa, an encroachment of palatable and woody flora, and a rise in fire activity. Differences with other published South-American records suggest that ecological consequences of megafaunal declines were habitat-specific. Overall, we show that ecosystems in the eastern Colombian Cordillera were highly sensitive to the decline of megafaunal populations. Under the current biodiversity crisis, management and conservation efforts must account for the effects of local herbivore declines on plant dispersal, on fire activity, and the potential loss of ecosystem services.

Being-with other predators: Cultural negotiations of Neanderthal-carnivore relationships in Late Pleistocene Europe

Late Pleistocene hominins co-evolved with non-analogue assemblages of carnivores and carnivorous omnivores. Although previous work has carefully examined the ecological and adaptive significance of living in such carnivore-saturated environments, surprisingly little attention has been paid to the social and cultural consequences of being-with, and adapting to, other charismatic predators and keystone carnivores. Focusing on Neanderthal populations in Western Eurasia, this paper draws together mounting archaeological evidence that suggests that some Late Pleistocene hominins devised specific behavioral strategies to negotiate their place within the vibrant carnivore guilds of their time. We build on integrative multispecies theory and broader re-conceptualizations of human-nature relations to argue that otherwise puzzling evidence for purported ‘symbolic’ behavior among Neanderthals can compellingly be re-synthesized with their ecology, settlement organization and lifeworld phenomenology. This re-framing of Neanderthal lifeways in the larger context of startling carnivore environments reveals that these hominins likely developed intimate, culturally mediated, and hence varied, bonds with raptor, hyena and bear others, rather than merely competing with them for resources, space and survival. This redressing of human-carnivore relations in the Middle Paleolithic yields important challenges for current narratives on evolving multispecies systems in the Late Pleistocene, complicating our understanding of Late Quaternary megafaunal extinctions and the roles of hominins in these processes.

Simultaneous extinction of Madagascar's megaherbivores correlates with late Holocene human-caused landscape transformation

Reconstructing the dynamics and drivers of late Quaternary megafaunal extinctions requires direct radiometric date series that are assessed within probabilistic statistical frameworks. Extinction chronologies are poorly understood for many tropical regions, including Madagascar, which had a diverse, now-extinct Holocene large vertebrate fauna including a “megaherbivore” guild of endemic hippopotami and elephant birds. Madagascar's megaherbivores likely played vital roles in regulating ecosystem structure and nutrient cycling, but few direct dates are available for megaherbivore specimens identified to species level, with uncertainty over when and why different representatives of this guild disappeared. Here, we conduct a new investigation into Malagasy megaherbivore extinction dynamics, including 30 new AMS dates and 63 audited published dates. We use Gaussian-resampled inverse-weighted McInerny (GRIWM) analysis to estimate species-specific extinction dates for three elephant bird species (Aepyornis hildebrandti, Mullerornis modestus, Vorombe titan), eggshell representing Aepyornis or Vorombe, and two hippo species (Hippopotamus lemerlei, H. madagascariensis), and to estimate extinction dates for megaherbivore communities in different biomes. Megaherbivores persisted for millennia after first human arrival. Extinction date estimates vary significantly between biomes, with disappearance from dry deciduous forest over a millennium earlier than other biomes, possibly reflecting local variation in megaherbivore population densities or human pressures. However, megaherbivore communities including all elephant bird and hippo species persisted elsewhere across Madagascar until ∼1200-900 bp, when they collapsed suddenly. Extinctions are closely correlated in time with intensive conversion of forests to grassland at ∼1100-1000 bp, probably associated with a shift to agro-pastoralism and representing a radical change in sustainability of prehistoric human interactions with biodiversity.

Coprophilous fungal spores: non-pollen palynomorphs for the study of past megaherbivores

AbstractSpores from coprophilous fungi are some of the most widely used non-pollen palynomorphs. Over the last decades, these spores have become increasingly important as a proxy to study the Pleistocene and Holocene megafauna. Although the number of types used in palaeoecology is relatively small, there is a wide range of coprophilous fungal taxa whose utility in palaeoenvironmental reconstruction remains under-researched. However, environmental and taphonomic factors influencing preservation and recovery of these spores are still poorly understood. Furthermore, our understanding of whether and how spores are transported across the landscape is limited.Dung fungal spore presence appears to correlate well with megaherbivore presence. However, depending on the site, some limitations can remain to quantitative reconstructions of megaherbivore abundance from dung fungal spore records. The presence of dung fungal spores is often more significant than their absence and variation in abundance with time should be interpreted with caution. Correlation with other proxies may provide a promising way forward.The majority of studies using dung fungal spores as an indicator for large herbivore abundance are of records of Late Pleistocene and Holocene age, with a focus on Late Quaternary megafaunal extinction. However, more research could potentially extend records further back in time.

Late Quaternary megafaunal extinctions in India: How much do we know?

Understanding global patterns of late Quaternary megafaunal extinction is impeded by geographic variation in data quality and quantity. The magnitude, timing and drivers of megafaunal extinctions remain poorly understood for India, a region with a strong history of palaeontological research. We review available data for all putative extinct Indian megafaunal taxa with direct or indirect reported evidence of potential survival into the global “megafaunal extinction window” (from ∼50,000 years onwards). Assessment of late Quaternary megafaunal species richness is confused by multiple levels of taxonomic uncertainty, including the relationship of named Late Pleistocene taxa to extant taxa, and nomenclatural confusion over correct species names. There is sufficient evidence to recognise up to four genuine global megafaunal species-level extinctions in India during the Late Pleistocene: two proboscideans (Palaeoloxodon namadicus, Stegodon sp.), a hippopotamus (Hexaprotodon sp.), and possibly a horse (Equus namadicus). A fifth extinct megafaunal species, the Indian aurochs Bos [primigenius] namadicus, definitely persisted into the Holocene. Other Indian late Quaternary megafaunal species (Rhinoceros spp., Bubalus palaeindicus, Sus “palaeindicus”, Crocodylus palaeindicus) are likely to be synonyms of extant species. Reconstructing regional extinction dynamics is further impeded by chronological uncertainty; however, attempts to obtain new dates for vertebrate samples from six late Quaternary sites in five regions were unsuccessful. Accurate understanding of the dynamics of megafaunal extinctions in India will require robust taxonomic, chronological and palaeoecological data, and we encourage further investigation of the region’s rich late Quaternary record.

Caught in a bottleneck: Habitat loss for woolly mammoths in central North America and the ice‐free corridor during the last deglaciation

AbstractAimIdentifying how climate change, habitat loss, and corridors interact to influence species survival or extinction is critical to understanding macro‐scale biodiversity dynamics under changing environments. In North America, the ice‐free corridor was the only major pathway for northward migration by megafaunal species during the last deglaciation. However, the timing and interplay among the late Quaternary megafaunal extinctions, climate change, habitat structure, and the opening and reforestation of the ice‐free corridor have been unclear.LocationNorth America.Time period15–10 ka.Major taxa studiedWoolly mammoth (Mammuthus primigenius).MethodsFor central North America and the ice‐free corridor between 15 and 10 ka, we used a series of models and continental‐scale datasets to reconstruct habitat characteristics and assess habitat suitability. The models and datasets include biophysical and statistical niche models Niche Mapper and Maxent, downscaled climate simulations from CCSM3 SynTraCE, LPJ‐GUESS simulations of net primary productivity (NPP) and woody cover, and woody cover based upon fossil pollen from Neotoma.ResultsThe ice‐free corridor may have been of limited suitability for traversal by mammoths and other grazers due to persistently low productivity by herbaceous plants and quick reforestation after opening 14 ka. Simultaneously, rapid reforestation and decreased forage productivity may have led to declining habitat suitability in central North America. This was possibly amplified by a positive feedback loop driven by reduced herbivory pressures, as mammoth population decline led to the further loss of open habitat.Main conclusionsDeclining habitat availability south of the Laurentide Ice Sheet and limited habitat availability in the ice‐free corridor were contributing factors in North American extinctions of woolly mammoths and other large grazers that likely operated synergistically with anthropogenic pressures. The role of habitat loss and attenuated corridor suitability for the woolly mammoth extinction reinforce the critical importance of protected habitat connectivity during changing climates, particularly for large vertebrates.

An unexpected record of an extinct water buffalo Bubalus murrensis (Berckhemer, 1927) in the Last Glacial in Europe and its implication for dispersal pattern of this species

An extinct thermophile European water buffalo Bubalus murrensis was recorded in the interglacials of the Middle and Late Pleistocene in Central and Western Europe. The species was unknown after the Eemian Interglacial (c. 123 ka) there and have never been found in Eastern Europe. Here we report on an unexpected record of this exotic species in the center of East European Plain near the Kolomna town (Moscow Region) more than 110 millennia later, in the Bølling – Allerød warming of the Last glacial. The unique paleontological discovery of the last European water buffalo in the center of Eastern Europe occupied mainly by a cold adapted so-called ‘Mammoth fauna’ allow us to discuss this unusual occurrence in paleoenvironmental context and suggest the model of dispersal and final extinction of the species. Based on recent integrated studies, we show that the species could persist in the Ponto-Caspian region and then spread northwards during the last Late Pleistocene warming. Main factors of its extinction could be the rapid global climatic changes and strong regional paleoenvironmental instability as well as increasing activity of Upper Paleolithic hunters. The discovery is important in the context of the late Quaternary megafaunal extinctions and a recent phenomenon of global warming.

Micro Methods for Megafauna: Novel Approaches to Late Quaternary Extinctions and Their Contributions to Faunal Conservation in the Anthropocene.

Drivers of Late Quaternary megafaunal extinctions are relevant to modern conservation policy in a world of growing human population density, climate change, and faunal decline. Traditional debates tend toward global solutions, blaming either dramatic climate change or dispersals of Homo sapiens to new regions. Inherent limitations to archaeological and paleontological data sets often require reliance on scant, poorly resolved lines of evidence. However, recent developments in scientific technologies allow for more local, context-specific approaches. In the present article, we highlight how developments in five such methodologies (radiocarbon approaches, stable isotope analysis, ancient DNA, ancient proteomics, microscopy) have helped drive detailed analysis of specific megafaunal species, their particular ecological settings, and responses to new competitors or predators, climate change, and other external phenomena. The detailed case studies of faunal community composition, extinction chronologies, and demographic trends enabled by these methods examine megafaunal extinctions at scales appropriate for practical understanding of threats against particular species in their habitats today.

Evolution and extinction of the giant rhinoceros Elasmotherium sibiricum sheds light on late Quaternary megafaunal extinctions

Understanding extinction events requires an unbiased record of the chronology and ecology of victims and survivors. The rhinoceros Elasmotherium sibiricum, known as the 'Siberian unicorn', was believed to have gone extinct around 200,000 years ago-well before the late Quaternary megafaunal extinction event. However, no absolute dating, genetic analysis or quantitative ecological assessment of this species has been undertaken. Here, we show, by accelerator mass spectrometry radiocarbon dating of 23 individuals, including cross-validation by compound-specific analysis, that E. sibiricum survived in Eastern Europe and Central Asia until at least 39,000 years ago, corroborating a wave of megafaunal turnover before the Last Glacial Maximum in Eurasia, in addition to the better-known late-glacial event. Stable isotope data indicate a dry steppe niche for E. sibiricum and, together with morphology, a highly specialized diet that probably contributed to its extinction. We further demonstrate, with DNA sequencing data, a very deep phylogenetic split between the subfamilies Elasmotheriinae and Rhinocerotinae that includes all the living rhinoceroses, settling a debate based on fossil evidence and confirming that the two lineages had diverged by the Eocene. As the last surviving member of the Elasmotheriinae, the demise of the 'Siberian unicorn' marked the extinction of this subfamily.

Climate-driven ecological stability as a globally shared cause of Late Quaternary megafaunal extinctions: the Plaids and Stripes Hypothesis.

ABSTRACTControversy persists about why so many large‐bodied mammal species went extinct around the end of the last ice age. Resolving this is important for understanding extinction processes in general, for assessing the ecological roles of humans, and for conserving remaining megafaunal species, many of which are endangered today. Here we explore an integrative hypothesis that asserts that an underlying cause of Late Quaternary megafaunal extinctions was a fundamental shift in the spatio‐temporal fabric of ecosystems worldwide. This shift was triggered by the loss of the millennial‐scale climate fluctuations that were characteristic of the ice age but ceased approximately 11700 years ago on most continents. Under ice‐age conditions, which prevailed for much of the preceding 2.6 Ma, these radical and rapid climate changes prevented many ecosystems from fully equilibrating with their contemporary climates. Instead of today's ‘striped’ world in which species' ranges have equilibrated with gradients of temperature, moisture, and seasonality, the ice‐age world was a disequilibrial ‘plaid’ in which species' ranges shifted rapidly and repeatedly over time and space, rarely catching up with contemporary climate. In the transient ecosystems that resulted, certain physiological, anatomical, and ecological attributes shared by megafaunal species pre‐adapted them for success. These traits included greater metabolic and locomotory efficiency, increased resistance to starvation, longer life spans, greater sensory ranges, and the ability to be nomadic or migratory. When the plaid world of the ice age ended, many of the advantages of being large were either lost or became disadvantages. For instance in a striped world, the low population densities and slow reproductive rates associated with large body size reduced the resiliency of megafaunal species to population bottlenecks. As the ice age ended, the downsides of being large in striped environments lowered the extinction thresholds of megafauna worldwide, which then increased the vulnerability of individual species to a variety of proximate threats they had previously tolerated, such as human predation, competition with other species, and habitat loss. For many megafaunal species, the plaid‐to‐stripes transition may have been near the base of a hierarchy of extinction causes whose relative importances varied geographically, temporally, and taxonomically.

Megafaunal isotopes reveal role of increased moisture on rangeland during late Pleistocene extinctions.

The role of environmental change in the late Pleistocene megafaunal extinctions remains a key question, owing in part to uncertainty about landscape changes at continental scales. We investigated the influence of environmental changes on megaherbivores using bone collagen nitrogen isotopes (n=684, 63 new) as a proxy for moisture levels in the rangelands that sustained late Pleistocene grazers. An increase in landscape moisture in Europe, Siberia and the Americas during the Last Glacial-Interglacial Transition (LGIT; ~25-10kyr bp) directly affected megaherbivore ecology on four continents, and was associated with a key period of population decline and extinction. In all regions, the period of greatest moisture coincided with regional deglaciation and preceded the widespread formation of wetland environments. Moisture-driven environmental changes appear to have played an important part in the late Quaternary megafaunal extinctions through alteration of environments such as rangelands, which supported a large biomass of specialist grazers. On a continental scale, LGIT moisture changes manifested differently according to regional climate and geography, and the stable presence of grasslands surrounding the central forested belt of Africa during this period helps to explain why proportionally fewer African megafauna became extinct during the late Pleistocene.

Late Quaternary megafaunal extinctions in southern Patagonia and their relation to environmental changes and human impacts

Late Quaternary megafaunal extinctions in southern Patagonia and their relation to environmental changes and human impacts

Bigger kill than chill: The uneven roles of humans and climate on late Quaternary megafaunal extinctions

Starting around 50,000 years ago, most large terrestrial animals went extinct in most continents. These extinctions have been attributed either to climatic changes, impacts of human dispersal across the world or a synergy among both. Most studies regarding these extinctions, however, have focused on particular continents or used low-resolution analyses. We used recent advances in fossil dating and past climatic models in a high-resolution quantitative analysis, comparing the explanatory power of the hypotheses at global scale. The timing of human arrival to each region was the best explanation for the extinctions. Climatic effects, where present, were additive rather than synergistic with human arrival. While climatic variation was a contributory cause that helped explaining the process, anthropogenic impacts were the necessary cause that drove it.

Variable impact of late-Quaternary megafaunal extinction in causing ecological state shifts in North and South America

Loss of megafauna, an aspect of defaunation, can precipitate many ecological changes over short time scales. We examine whether megafauna loss can also explain features of lasting ecological state shifts that occurred as the Pleistocene gave way to the Holocene. We compare ecological impacts of late-Quaternary megafauna extinction in five American regions: southwestern Patagonia, the Pampas, northeastern United States, northwestern United States, and Beringia. We find that major ecological state shifts were consistent with expectations of defaunation in North American sites but not in South American ones. The differential responses highlight two factors necessary for defaunation to trigger lasting ecological state shifts discernable in the fossil record: (i) lost megafauna need to have been effective ecosystem engineers, like proboscideans; and (ii) historical contingencies must have provided the ecosystem with plant species likely to respond to megafaunal loss. These findings help in identifying modern ecosystems that are most at risk for disappearing should current pressures on the ecosystems' large animals continue and highlight the critical role of both individual species ecologies and ecosystem context in predicting the lasting impacts of defaunation currently underway.

A Quantitative Model for Distinguishing Between Climate Change, Human Impact, and Their Synergistic Interaction as Drivers of the Late Quaternary Megafaunal Extinctions

A simple quantitative approach is presented for determining the relative importance of climate change and human impact in driving late Quaternary megafaunal extinctions. This method is designed to determine whether climate change or human impact alone can account for these extinctions, or whether both were important, acting independently (additively) and/or synergistically (multiplicatively). This approach is applied to the megafaunal extinction in the Última Esperanza region of southern Chile. In this region, there is a complex pattern of extinction. Records of environmental change include temperature proxies and pollen records that capture the transition from cold grasslands to warmer, moister forests, as well as evidence of initial human arrival. Uncertainty in extinction times and time of human arrival complicates the analysis, as does uncertainty about the size of local human populations, and the nature, strength, and persistence of their impacts through the late Pleistocene and early Holocene. Results of the Ultima Esperanza analysis were equivocal, with evidence for climate- and human-driven extinction, with each operating alone or additively. The results depend on the exact timing of extinctions and human arrival, and assumptions about the kinds of pressures humans put on the megafauna. There was little evidence for positive synergistic effects, while the unexpected possibility of negative synergistic interactions arose in some scenarios. Application of this quantitative approach highlights the need for higher precision dating of the extinctions and human arrival, and provides a platform for sharpening our understanding of these megafaunal extinctions.

Robustness despite uncertainty: regional climate data reveal the dominant role of humans in explaining global extinctions of Late Quaternary megafauna

Debate over the Late Quaternary megafaunal extinctions has focussed on whether human colonisation or climatic changes were more important drivers of extinction, with few extinctions being unambiguously attributable to either. Most analyses have been geographically or taxonomically restricted and the few quantitative global analyses have been limited by coarse temporal resolution or overly simplified climate reconstructions or proxies. We present a global analysis of the causes of these extinctions which uses high‐resolution climate reconstructions and explicitly investigates the sensitivity of our results to uncertainty in the palaeological record. Our results show that human colonisation was the dominant driver of megafaunal extinction across the world but that climatic factors were also important. We identify the geographic regions where future research is likely to have the most impact, with our models reliably predicting extinctions across most of the world, with the notable exception of mainland Asia where we fail to explain the apparently low rate of extinction found in in the fossil record. Our results are highly robust to uncertainties in the palaeological record, and our main conclusions are unlikely to change qualitatively following minor improvements or changes in the dates of extinctions and human colonisation.

Solving the woolly mammoth conundrum: amino acid 15N-enrichment suggests a distinct forage or habitat

Understanding woolly mammoth ecology is key to understanding Pleistocene community dynamics and evaluating the roles of human hunting and climate change in late Quaternary megafaunal extinctions. Previous isotopic studies of mammoths’ diet and physiology have been hampered by the ‘mammoth conundrum’: woolly mammoths have anomalously high collagen δ15N values, which are more similar to coeval carnivores than herbivores, and which could imply a distinct diet and (or) habitat, or a physiological adaptation. We analyzed individual amino acids from collagen of adult woolly mammoths and coeval species, and discovered greater 15N enrichment in source amino acids of woolly mammoths than in most other herbivores or carnivores. Woolly mammoths consumed an isotopically distinct food source, reflective of extreme aridity, dung fertilization, and (or) plant selection. This dietary signal suggests that woolly mammoths occupied a distinct habitat or forage niche relative to other Pleistocene herbivores.

Late Quaternary megafaunal extinctions on the continents: a short review

This paper provides an overview of the contentious issue of global megafaunal extinctions in the Late Quaternary. The main proposed causes are ‘overkill’, environmental change or a combination of both. There are major objections to the other suggested causes. Extinctions were highly variable in their severity between different zoogeographical regions, with the greatest impact in North America, South America and Australia, but also substantial in northern Eurasia. Sub‐Saharan Africa and Southern Asia were much less affected. For northern Eurasia, detailed chronologies show a staggered extinction pattern, in which each megafaunal species exhibits unique and complex distributional shifts, culminating in extinction for some species and survival in others. Environmental drivers were clearly very important, although the possible role of humans is not yet clear. Alaska/Yukon also has a good radiocarbon record which also suggests a staggered extinction pattern. However, the available data for the rest of North America are largely unsatisfactory. South America also boasted spectacular extinct megafauna, but again the currently available dates are insufficient to reliably discern patterns or possible causes. Australia and New Guinea also suffered major losses, but extinctions probably occurred much earlier than elsewhere, so that establishing a chronology is especially difficult. Africa and Southern Asia have the least available data. In order to make meaningful progress, it is vital to establish a large database of reliable radiocarbon dates for each region made directly on securely identified megafaunal remains. The need is for much more high quality data, not more debate based on imperfect evidence. Copyright © 2014 John Wiley & Sons, Ltd.

Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction.

The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.

Ecological impacts of the late Quaternary megaherbivore extinctions

As a result of the late Quaternary megafaunal extinctions (50,000-10,000 before present (BP)), most continents today are depauperate of megaherbivores. These extinctions were time-transgressive, size- and taxonomically selective, and were caused by climate change, human hunting, or both. The surviving megaherbivores often act as ecological keystones, which was likely true in the past. In spite of this and extensive research on the causes of the Late Quaternary Extinctions, the long-term ecological consequences of the loss of the Pleistocene megafauna remained unknown until recently, due to difficulties in linking changes in flora and fauna in paleorecords. The quantification of Sporormiella and other dung fungi have recently allowed for explicit tests of the ecological consequences of megafaunal extirpations in the fossil pollen record. In this paper, I review the impacts of the loss of keystone megaherbivores on vegetation in several paleorecords. A growing number of studies support the hypothesis that the loss of the Pleistocene megafauna resulted in cascading effects on plant community composition, vegetation structure and ecosystem function, including increased fire activity, novel communities and shifts in biomes. Holocene biota thus exist outside the broader evolutionary context of the Cenozoic, and the Late Quaternary Extinctions represent a regime shift for surviving plant and animal species.