Late Pleistocene Extinctions Research Articles

Australia's recently established predators restore complexity to food webs simplified by extinction.

Since prehistory, humans have altered the composition of ecosystems by causing extinctions and introducing species. However, our understanding of how waves of species extinctions and introductions influence the structure and function of ecological networks through time remains piecemeal. Here, focusing on Australia, which has experienced many extinctions and introductions since the Late Pleistocene, we compared the functional trait composition of Late Pleistocene (130,00-115,000 years before present [ybp]), Holocene (11,700-3,000 ybp), and current Australian mammalian predator assemblages (≥70% vertebrate meat consumption; ≥1kg adult body mass). We then constructed food webs for each period based on estimated prey body mass preferences. We found that introduced predators are functionally distinct from extinct Australian predators, but they rewire food webs toward a state that closely resembles the Late Pleistocene, prior to the megafauna extinctions. Both Late Pleistocene and current-day food webs consist of an apex predator and three smaller predators. This leads to food web networks with a similar total number of links, link densities, and compartmentalizations. However, this similarity depends on the presence of dingoes: in their absence, food webs become simplified and reminiscent of those following the Late Pleistocene extinctions. Our results suggest that recently established predators, even those implicated in species extinctions and declines, can restore complexity to food webs simplified by extinction.

After the mammoths: The ecological legacy of late Pleistocene megafauna extinctions

Abstract The significant extinctions in Earth history have largely been unpredictable in terms of what species perish and what traits make species susceptible. The extinctions occurring during the late Pleistocene are unusual in this regard, because they were strongly size-selective and targeted exclusively large-bodied animals (i.e., megafauna, >1 ton) and disproportionately, large-bodied herbivores. Because these animals are also at particular risk today, the aftermath of the late Pleistocene extinctions can provide insights into how the loss or decline of contemporary large-bodied animals may influence ecosystems. Here, we review the ecological consequences of the late Pleistocene extinctions on major aspects of the environment, on communities and ecosystems, as well as on the diet, distribution and behavior of surviving mammals. We find the consequences of the loss of megafauna were pervasive and left legacies detectable in all parts of the Earth system. Furthermore, we find that the ecological roles that extinct and modern megafauna play in the Earth system are not replicated by smaller-bodied animals. Our review highlights the important perspectives that paleoecology can provide for modern conservation efforts.

Re‐evaluating the evidence for late‐surviving megafauna at Nombe rockshelter in the New Guinea highlands

AbstractThe causes of the Late Pleistocene extinction of most larger‐bodied animals on the Australian continent have long been controversial. This is due, in no small part, to inadequate knowledge of exactly when these species were lost from different ecosystems. The Nombe rockshelter in the highlands of Papua New Guinea is one of very few sites on Sahul with as‐yet‐unrefuted evidence for the survival of megafaunal species until more recently than 40 thousand years (ka) ago. However, our understanding of the age of this site has been based on radiocarbon dating. Here we present new U–Th ages on large marsupial specimens from the deposit and identify a range of postcranial elements to species that include the diprotodontid Hulitherium tomasettii, kangaroo Protemnodon tumbuna and thylacine Thylacinus cynocephalus. Direct U–Th ages of 27–22 ka ago on faunal remains of Protemnodon tumbuna and another large unidentified macropodid are consistent with the existing radiocarbon chronology, yet are minimum ages due to the potential for post‐depositional uptake of 238U and stratigraphic reworking. Pollen analyses indicate perhumid, montane forests dominated by Nothofagus persisted, with minimal human disturbance from at least c.26–20 ka ago up to the terminal Pleistocene. Collagen fingerprinting (ZooMS) demonstrates the potential of protein‐based identification of megafaunal remains at Nombe in the future. This study leaves open the possibility of extended coexistence between some megafaunal species in the montane rainforests of New Guinea and intermittently visiting groups of people, and underscores the need for further investigation of the Nombe deposit. Although preliminary, these findings reinforce the view that debates regarding megafaunal extinctions on Sahul require a greater appreciation of species‐specific temporalities and the degrees of human impact on diverse habitats across the continent.

POST-PLEISTOCENE HORSES (EQUUS) FROM MÉXICO

Abstract For more than a century many paleontologists, biologists, paleoecologists, and archaeologists have contended that Equus species (American horse) became extinct on the North American continent by about 13,000 calibrated years BP – all part of the Late Pleistocene (Ice Age) extinction event. The paleontological project presented here that focuses on Equus from Rancho Carabanchel, San Luis Potosí, México became chronologically intriguing to us in having the horse consistently radiometrically dating into the Holocene, well beyond the presumed extinction event. Our approach to this observation was to conduct successive radiocarbon dates (n=19) tied as closely as possible to fossil remains and to stratigraphic units. The remains of the extant horse, Equus caballus, were recovered only in the upper-most Unit I while the extinct Equus cf. mexicanus, E. cf. conversidens, and E. cf. tau were recovered from the underlying Units II – VI of the late Holocene to approximately 45,000 calibrated years ago. We discuss how our data adds to the growing information which implies that horses may have persisted in this region of México well after the classical Late Pleistocene extinction event. Our conclusions may well illustrate that the extinction episode was actually a process lasting well into the Holocene and was not the event that many paleoecologists and archaeologist envision.

History of canids in Chile and impacts on prey adaptations.

Artiodactyl prey species of Chile, especially guanacos (Lama guanicoe), are reported to be very susceptible to predation by pack‐hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack‐hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies, and hunting behavior. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviors of guanacos: predator inspection of ambush predators, for example, Puma concolor, and rushing at and kicking smaller cursorial predators, for example, Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group‐hunting canids east of the Andes, there were no native species creating group‐hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group‐hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.

Overkill and the North American archaeological record—not guilty by association? A comment on Wolfe and Broughton (2020)

The “associational critique” holds that there are too few archaeological kill/scavenging sites to support the hypothesis that human hunting caused the late Pleistocene extinction of 38 genera of primarily large mammals. Wolfe and Broughton (2020) assessed this critique on both theoretical and empirical grounds and found it wanting, with a focus on the arguments presented in Grayson and Meltzer (2015). We welcome their evaluation, including their effort to improve on our prior analyses. However, we are unconvinced by their assertion that hunters will always pursue large ungulates on encounter. We also reject their conclusion there is no systematic difference in the abundance of extant and extinct taxa in terminal Pleistocene archaeological contexts since they made two errors that undermine their analysis. First, they confounded calibrated and uncalibrated radiocarbon years. Second, they failed to note the parameters of the Cannon and Meltzer (2004) study on which their tally of archaeological kill/scavenging sites of extant taxa is based. With these mistakes corrected, the results confirm what we showed previously: extant large mammals occur in kill/scavenging sites far more often than extinct forms. This result also supports our previous suggestion that the now-extinct fauna had either already disappeared or was much reduced in abundance by the time people arrived on the landscape.

Patterns and drivers of genetic diversity among Felidae species

Since the late Pleistocene, species in the order Carnivora have experienced a drastic reduction in their populations and distributions. However, the global genetic diversity patterns among terrestrial carnivores have not been investigated. Using felid species as model, we characterized the genetic variation within their populations among continents, between tropical and non-tropical regions, and in relation to human activities. We then evaluated how species traits influence the observed patterns of interspecific genetic diversity. Through data collected from 135 population genetic studies conducted on 28 wild felid species (70% of the described species), data analyses using GLMM modelling showed that the populations in Africa and South America have significantly higher heterozygosity and allelic richness than those in other continents. The Asiatic lions have the least genetic diversity compared to other felids in the world. Threatened species have significantly lower genetic diversity compared to low-risk species as predicted. However, genetic diversity was not related to species body mass or geographic range. We found generation length to be an important variable explaining genetic diversity variation, in which species with short generation length have reduced genetic diversity. Furthemore, the combination of generation length, habitat and home range size captures the variation in heterozygosity significantly better. Species dependent on closed-habitat and with large home range size have reduced heterozygosity compared to their counterparts. Our results allow to identify priority felid species vulnerable to loss of genetic diversity for further conservation studies, and provide an insight into the possible genetic consequences of the late Pleistocene extinctions.

Were human-introduced diseases the responsible for Pleistocene-Holocene megafaunal extinctions? First evidence from South America

Diverse hypotheses have been proposed with the aim to explain the extinction of Late Pleistocene/Holocene mammals, including the Megafauna from America. Some authors support that human being was the direct responsible of extinction by means of intensive hunting, as proposed by the “blitzkrieg” or overkilling hypothesis. However, evidence is not conclusive. As is well known by biologists, exotic diseases may play an important role in local extinction of diverse vertebrates. On this basis, some speculated that the arrival of man may also have introduced new diseases that may have played an important role on native mammals, especially megafaunal populations, probably constituting a key factor on their extinction. Recent findings of the parasite Fasciola hepatica in endemic deer from Holocene sites in Patagonia (and also probably from camelids in Peru) previous to Hispanic colonization constitute indirect evidence that may sustain this hypothesis. Because one of the main definite host of this parasite are humans, this potential disease may have been introduced by human populations as hosts and then disperse through the entire continent, as evidenced by the finding of Fasciola hepatica in Patagonia. Its presence in endemic deer and camelids previous to Hispanic colonization, reinforces the proposal that human-related diseases may have played some role in Late Pleistocene extinction of large native mammals.

Extinction in the Anthropocene.

Samuel Turvey and Jennifer Crees introduce the effects of humans on biodiversity.

The Exergy Footprint as a Sustainability Indicator: An Application to the Neanderthal–Sapiens Competition in the Late Pleistocene

A thermodynamic analysis of population dynamics and of sustainability provides rigor to many important issues. In this work, the “system society” is analysed in connection with the “system environment” using an exergy metric, and the method includes an internalization of the externalities (capital, labour, environmental effects) conducted on the basis of a “system + environment” balance. In this perspective, this study investigates the Late Pleistocene extinction of the Homo neanderthalensis, which took place in a geologically short time and in the presence of a competing species, the Homo sapiens. The case in study is not trivial, and its choice not casual: in those times, the only factor that could lead to an advantage of one group over the other was their respective resource use intensity. A specific indicator, the exergy footprint (EF), is here applied to measure the total amount of primary resources required to produce a certain (material or immaterial) commodity, including the resources needed for the physical survival of the individuals. On the basis of the available data, the results of a steady-state analysis show that the EF of the Neanderthal was higher than that of the Sapiens, and that with both species sharing the same ecological niche in a time of dwindling resources, the less frugal of the two was also more fragile in an evolutionary sense.

Enamel hypoplasia and dental wear of North American late Pleistocene horses and bison: an assessment of nutritionally based extinction models

AbstractApproximately 50,000–11,000 years ago many species around the world became extinct or were extirpated at a continental scale. The causes of the late Pleistocene extinctions have been extensively debated and continue to be poorly understood. Several extinction models have been proposed, including two nutritionally based extinction models: the coevolutionary disequilibrium and mosaic-nutrient models. These models draw upon the individualistic response of plant species to climate change to present a plausible scenario in which nutritional stress is considered one of the primary causes for the late Pleistocene extinctions.In this study, we tested predictions of the coevolutionary disequilibrium and mosaic-nutrient extinction models through the study of dental wear and enamel hypoplasia ofEquusandBisonfrom various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results that are consistent with predictions established for the coevolutionary disequilibrium model, but not for the mosaic-nutrient model. These ungulate species show statistically different dental wear patterns (suggesting dietary resource partitioning) during preglacial and full-glacial time intervals, but not during the postglacial in accordance with predictions of the coevolutionary disequilibrium model. In addition to changes in diet, these ungulates, specifically the equid species, show increased levels of enamel hypoplasia during the postglacial, indicating higher levels of systemic stress, a result that is consistent with the models tested and with other climate-based extinction models. The extent to which the increase in systemic stress was detrimental to equid populations remains to be further investigated, but suggests that environmental changes during the late Pleistocene significantly impacted North American equids.

First record of avian extinctions from the Late Pleistocene and Holocene of Timor Leste

Timor has yielded the earliest evidence for modern humans in Wallacea, but despite its long history of modern human occupation, there is little evidence for human-induced Late Pleistocene extinctions. Here, we report on Late Pleistocene and Holocene bird remains from Jerimalai and Matja Kuru 1, sites that have yielded extensive archaeological sequences dating back to >40 ka. Avian remains are present throughout the sequence, and quails (Phasianidae), buttonquails (Turnicidae) and pigeons (Columbidae) are the most abundant groups. Taphonomic analyses suggest that the majority of bird remains, with the exception of large-bodied pigeons, were accumulated by avian predators, likely the Barn owl Tyto sp. All species represent extant taxa that are still present on Timor today, with the exception of a crane, Grus sp., from the Late Pleistocene of Jerimalai, and a large buttonquail, Turnix sp., from Matja Kuru 1. The crane likely represents an extirpated population of cranes, which were much more widespread throughout the Indonesian archipelago during the Quaternary. The large buttonquail is present at Matja Kuru 1 alongside the extant T. maculosus until at least 1372–1300 cal BP. These two species represent the first records of avian extinctions on Timor. However, a causal relationship between the extinction of these two taxa and human impact cannot be demonstrated at this point.

Trophic rewilding: impact on ecosystems under global change.

Human-induced global change is increasingly affecting life on our planet, including living conditions for humans themselves as well as the resources we depend on [1,2]. As a result, species diversity is strongly declining [3–5]. The Living Planet Index shows a 58% global decline in populations of amphibians, fish, reptiles, mammals and birds between 1970 and 2012, varying from 36 to 38% in terrestrial and marine ecosystems to 81% in freshwater habitat [6]. Habitat loss or degradation and overexploitation are the main causes of these steep declines. Since the worldwide expansion of modern humans ( Homo sapiens ) began, humans have overexploited vertebrates, with a bias to the largest animals being extirpated first, from the Late Pleistocene extinctions of terrestrial megafauna to the ongoing declines of terrestrial, marine and freshwater large-bodied animals [7–11]. There is increasing evidence that this global wildlife loss, or defaunation, does not only imply the loss of charismatic animals but also the functions they have in ecosystems [12–16]. To restore these missing functions, a novel ecological restoration technique has emerged, referred to as rewilding [17]. Rewilding aims to restore natural processes in ecosystems in general, and often focuses on re-introduction of missing large wildlife species or, in case these went extinct, their proxies [18]. Rewilding is increasingly implemented in practice globally, with a strong emphasis on Europe and the re-introduction of large herbivores [19,20]. Rewilding has recently been described as ‘a captivating, controversial, twenty-first century concept to address ecological degradation’ [20]. Most rewilding initiatives fit the concept of trophic rewilding, defined as an ecological restoration strategy that uses species introductions to restore top-down trophic interactions and associated trophic cascades to promote …

The Rise of the Anthroposphere since 50,000 Years: An Ecological Replacement of Megaherbivores by Humans in Terrestrial Ecosystems?

Megaherbivores fulfilled a number of important ecological function in terrestrial ecosystems and behaved as ecological engineers since 300 million years until around 12,000 years ago. The late Pleistocene extinction led to the loss of important ecological functions that were partially restore by agriculturists humans through an ecological replacement. Understanding better the differences and similarities in the ecological impact of megaherbivores and agricultural humans should help to predict the future of terrestrial ecosystems.

A middle Holocene steppe bison and paleoenvironments from the Versleuce Meadows, Whitehorse, Yukon, Canada

A partial skeleton of a bison was recovered during residential house construction in Whitehorse, Yukon, Canada. The specimen represents a young (estimated 6 year old) bison individual that died, was partially scavenged by carnivores, and subsequently buried by calcareous silt sediment in a pond or small lake during the middle Holocene, ∼5400 years ago. Palaeoenvironmental data, including molluscs, pollen, vascular plant, and bryophyte macrofossils demonstrate that the small waterbody was surrounded by white spruce dominated boreal forest. Morphometric analysis of the skeleton reveals that its taxonomic affinity is ambiguous, likely owing to it representing an ontogenetically young individual, though it does share some cranial and horn core characteristics of named species such as Bison occidentalis or Bison priscus. Mitochondrial genomic data confirm that this bison belongs to Clade 2A (northern clade), which represents Pleistocene steppe bison (B. cf. priscus) in Beringia through the Holocene and is not represented in living bison species. These data further demonstrate that northern steppe bison population survived the late Pleistocene extinction event, persisted locally in southern Yukon into the Holocene, and are best characterized as a species with a high degree of morphological variability and ecological flexibility.

Correction: Corrigendum: Megafaunal isotopes reveal role of increased moisture on rangeland during late Pleistocene extinctions

Nature Ecology & Evolution 1, 0125 (2017); published 18 April 2017; corrected 5 June 2017. The Supplementary Information files that were originally published with the Article were not the intended final files. Both files have been updated.

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.

Seed dispersal kernel of the largest surviving megaherbivore—the African savanna elephant

AbstractOwing to the late Pleistocene extinctions, the megafauna of Europe, Australia and the Americas disappeared, and with them the dispersal service they offered megafaunal fruit. The African savanna elephant, the largest remaining megaherbivore, offers valuable insights into the seed dispersal services provided by extinct megafauna in prehistoric times. Elephant seed dispersal studies have for the most part concentrated on African and Asian forest elephants. African savanna elephants are morphologically distinct from their forest counterparts. Like the forest elephants they consume large quantities of fruit from a large number of tree species. Despite this little is known of the savanna trees that rely on elephants for their dispersal or the spatial scale at which these seeds are dispersed. We combined information from feeding trials conducted on four park elephants with field telemetry data from 38 collared elephants collected over an 8‐year period in APNR/Kruger National Park to assess the seed dispersal service provided by savanna elephants. This study provides the first detailed account of the spatial scale at which African savanna elephants disperse seeds. Our mechanistic model predicts that 50 percent of seeds are carried over 2.5 km, and distances up to 65 km are achievable in maximum gut passage time. These findings suggest the savanna elephant as the longest distance terrestrial vertebrate disperser yet investigated. Maintaining their ecological role as a seed disperser may prove a significant factor in the conservation of large‐fruited tree diversity within the savannas. These results suggest that extinct megafauna offered a functionally unique dispersal service to megafaunal fruit.

Early cave art and ancient DNA record the origin of European bison.

The two living species of bison (European and American) are among the few terrestrial megafauna to have survived the late Pleistocene extinctions. Despite the extensive bovid fossil record in Eurasia, the evolutionary history of the European bison (or wisent, Bison bonasus) before the Holocene (<11.7 thousand years ago (kya)) remains a mystery. We use complete ancient mitochondrial genomes and genome-wide nuclear DNA surveys to reveal that the wisent is the product of hybridization between the extinct steppe bison (Bison priscus) and ancestors of modern cattle (aurochs, Bos primigenius) before 120 kya, and contains up to 10% aurochs genomic ancestry. Although undetected within the fossil record, ancestors of the wisent have alternated ecological dominance with steppe bison in association with major environmental shifts since at least 55 kya. Early cave artists recorded distinct morphological forms consistent with these replacement events, around the Last Glacial Maximum (LGM, ∼21–18 kya).

A late Quaternary vertebrate deposit in Kudjal Yolgah Cave, south‐western Australia: refining regional late Pleistocene extinctions

ABSTRACTWe describe the stratigraphy and chronology of Kudjal Yolgah Cave in south‐western Australia, a late Quaternary deposit pre‐ and post‐dating regional human arrival and preserving fossils of extinct and extant fauna. Single‐grain optically stimulated luminescence (OSL) dating shows that seven superposed units were deposited over the past 80 ka. Remains of 16 mammal species have been found at the site, all of them represented in Unit 7, for which seven OSL ages indicate accumulation between 80 and 41 ka. Single‐grain OSL equivalent dose distribution patterns show no evidence of reworking of older or younger sediments into Unit 7, but late Holocene charcoal has been washed into the top of it from adjacent Unit 2, deposited 1.2 ka ago. Six species that failed to survive the Pleistocene are recorded in Unit 7, but only the south‐western wombatVombatus hackettiis recorded in younger units. Two species, the large extinct kangaroosProtemnodonsp.cf.P. roechusandProcoptodon browneorum, are represented by articulated specimens near the top of Unit 7, immediately adjacent to an OSL sediment sample dated to 41 ± 2 ka. These are the youngest reliably dated records of these genera from mainland Australia, and among the youngest megafaunal remains from the continent. All species currently known from the middle Pleistocene of the south‐west persisted into the late Pleistocene, which removes a key pillar supporting the argument against a driving role for human impacts in the extinctions.