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opencc-zeroDec 2012View details →

Data from: Recovery of benthic marine communities from the end-Permian mass extinction at the low-latitudes of Eastern Panthalassa

Based on the quantitative community analysis using species-level identifications, we track the restoration of benthic ecosystems after the end-Permian mass extinction throughout the Lower Triassic of the western USA. New data on the palaeoecology of the Thaynes Group and Sinbad Formation are provided, which fill a gap between the recently studied palaeoecology of the Griesbachian–Dienerian Dinwoody Formation and the Spathian Virgin Formation. In the Sinbad Formation and Thaynes Group, 17 species (12 genera) of bivalves, 7 species and genera of gastropods and 2 species and genera of brachiopods are recognized. The new bivalve genus Confusionella (Pteriidae) is described. A comprehensive review of the whole Lower Triassic succession of benthic ecosystems of the western USA indicates that mid- and inner shelf environments show incipient recovery signals around the Griesbachian–Dienerian transition, during the Smithian and, most profound, during the early Spathian. Ecological data from youngest strata of the Dinwoody Formation as well as stratigraphic ranges of species suggest that the late Dienerian was likely a time interval of environmental stress for benthic ecosystems. Despite some evidence for short-term environmental disturbances (e.g. shift of dominant taxa, transient drop in alpha-diversity) during the Smithian–Spathian transition, benthic ecosystems did not show any notable taxonomic turnover at that time, in contrast to the major crisis that affected ammonoids and conodonts. Whereas alpha-diversity of benthic communities generally increased throughout the Early Triassic, beta-diversity remained low, which reflects a persistently wide environmental range of benthic species. This observation is in accordance with a recently proposed model that predicts a time lag between increasing within-habitat diversity (alpha-diversity) and the onset of taxonomic differentiation between habitats (beta-diversity) during biotic recoveries from mass extinction events. The observation that beta-diversity had not significantly increased during the Early Triassic might also provide an explanation for the comparably sluggish increase in benthic diversity during that time, which has previously been attributed to persistent environmental stress.

opencc-zeroDec 2018View details →

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

Approximately 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: 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 of Equus and Bison from various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results which 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 which 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.

opencc-zeroJun 2021View details →

Datasets associated with: Late Holocene spread of pastoralism coincides with endemic megafaunal extinction on Madagascar

Recently expanded estimates for when humans arrived on Madagascar (up to ~10,000 years ago) highlight questions about the causes of the island's relatively late megafaunal extinctions (~2000-500 years ago). Introduced domesticated animals could have contributed to extinctions, but the arrival times and past diets of exotic animals are poorly known. To conduct the first explicit test of the potential for competition between introduced livestock and extinct endemic megafauna in southern and western Madagascar, we generated new radiocarbon and stable carbon and nitrogen isotope data from the bone collagen of introduced ungulates (zebu cattle, ovicaprids, and bushpigs, n=66) and endemic megafauna (pygmy hippopotamuses, giant tortoises, and elephant birds, n=68) and combined these data with existing data from endemic megafauna (n=282, including giant lemurs). Radiocarbon dates confirm that introduced and endemic herbivores briefly overlapped chronologically in this region between 1000 and 800 calibrated years before present (cal BP). Moreover, stable isotope data suggest that goats, tortoises, and hippos had broadly similar diets or exploited similar habitats. These data support the potential for both direct and indirect forms of competition between introduced and endemic herbivores. We argue that competition with introduced herbivores, mediated by opportunistic hunting by humans and exacerbated by environmental change, contributed to the late extinction of endemic megafauna on Madagascar.

FIGURES 1–4 in The first extinct species of Monolepta Chevrolat (Coleoptera: Chrysomelidae Galerucinae) from Bitterfeld amber, described using X-ray micro-computed tomography

FIGURES 1–4. Photomicrographs of Monolepta rappsilberi sp. nov., holotype, No T-I-K-30 [CIR], female: 1—habitus, dorsal view; 2—habitus, ventral view; 3—details of abdomen; 4—tarsi. Abbreviations: ca—carina, mst—mesotibia, mtt—metatibia, prt—protibia, v1–v5—abdominal ventrites 1–5. Not reproduced to the same scale.

FIGURES 12–13. X in The first extinct species of Monolepta Chevrolat (Coleoptera: Chrysomelidae Galerucinae) from Bitterfeld amber, described using X-ray micro-computed tomography

FIGURES 12–13. X-ray micro-CT renderings of Monolepta rappsilberi sp. nov., holotype, No T-I-K-30 [CIR]: 12—head (right antenna removed), frontal view; 13—details of forebody without legs, ventral view. Abbreviations: as—antennal sock- et, c—clypeus, fc—frontal carina, ft—frontal tubercle, l—labrum, mp3–mp4—maxillary palpomeres 3–4, os—orbital sulcus, scs—supracallar sulcus, sos—supraorbital sulcus. Scale bar represents 0.5 mm.

FIGURES 5–8. X in The first extinct species of Monolepta Chevrolat (Coleoptera: Chrysomelidae Galerucinae) from Bitterfeld amber, described using X-ray micro-computed tomography

FIGURES 5–8. X-ray micro-CT renderings of Monolepta rappsilberi sp. nov., holotype, No T-I-K-30 [CIR], habitus: 5—dorsal view; 6—ventral view; 7—right lateral vie; 8—left lateral view. Scale bar represents 1.0 mm.

FIGURES 9–11. X in The first extinct species of Monolepta Chevrolat (Coleoptera: Chrysomelidae Galerucinae) from Bitterfeld amber, described using X-ray micro-computed tomography

FIGURES 9–11. X-ray micro-CT renderings of Monolepta rappsilberi sp. nov., holotype, No T-I-K-30 [CIR]: 9—habitus, caudal view; 10—details of forebody, dorsal view; 11—habitus without legs, ventral view. Not reproduced to the same scale.

opencc-zeroJul 2021View details →

Analyzing time-energy constraints to understand the links between environmental change and local extinctions in terrestrial ectotherms

Accelerated extinction rates have prompted an increased focus on the interplay between environmental change and species response. The effects of environmental change on thermal opportunity are typically considered through a climate change context. However, habitat alteration can also have strong effects on the thermal environment. Additionally, habitat alteration is considered a leading factor of species extinction, yet few studies address the influence of habitat alteration on thermal opportunity and time-energy budgets in at-risk species. Here we show the strong effects that habitat degradation can have on thermal opportunity, time energy-budgets, and life history demographics of local populations. In the Ozark Mountains of northern Arkansas, woody vegetation encroachment has resulted in a shift in life history traits that appears to play an important role in recent extirpations of Eastern Collared Lizards (Crotaphytus collaris). Populations in degraded habitats experienced a decline in thermal opportunity and less time-at-body temperatures (time-at-Tb) suitable for digestion compared to those in intact habitats. We used our data to model the effect of reduced time-at-Tb on the net assimilated energy available for growth and reproduction. Our model predicts a ca. 46% decline in annual fecundity of individuals – which is similar to empirical observations of reproduction of C. collaris populations in degraded habitats (~49%). We conclude that C. collaris in degraded habitats experienced reduced growth and reproduction primarily as a result of constrained thermal opportunity leading to a decline in digestive processing rates. Our study applies an under-appreciated approach to identify the biophysical and time-energy effects of habitat alteration.

opencc-zeroJul 2021View details →

Data from: Assessing bite force estimates in extinct mammals and archosaurs using phylogenetic predictions

Bite force is an ecologically important biomechanical performance measure is informative in inferring the ecology of extinct taxa. However, biomechanical modelling to estimate bite force is associated with some level of uncertainty. Here, I assess the accuracy of bite force estimates in extinct taxa using a Bayesian phylogenetic prediction model. I first fitted a phylogenetic regression model on a training set comprising extant data. The model predicts bite force from body mass and skull width while accounting for differences owning to biting position. The posterior predictive model has a 93% prediction accuracy as evaluated through leave-one-out cross-validation. I then predicted bite force in 37 species of extinct mammals and archosaurs from the posterior distribution of predictive models. Biomechanically estimated bite forces fall within the posterior predictive distributions for all except four species of extinct taxa and are thus as accurate as that predicted from body size and skull width, given the variation inherent in extant taxa and the amount of time available for variance to accrue. Biomechanical modelling remains a valuable means to estimate bite force in extinct taxa and should be reliably informative of functional performances and serve to provide insights into past ecologies.

FIGURE 8 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 8. Psychotria veillonii Barrabé. A. Branches with young inflorescences; B. Detail of the young inflorescence; C. Fruit apex; D. Fruit; E. Dorsal face of the pyrene; F. Ventral face of the pyrene; G. Lateral surface of the pyrene; H. Cross section of the pyrene. Drawn by Michèle Magat.

FIGURE 6 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 6. Psychotria nigotei Barrabé. A. Branches with inflorescences and flowers at anthesis; B. Detail of the adaxial leaf apex; C. Stipule; D. Detail of the calyx; E. Flower at anthesis; F. Stigmas; G. Details of stamens; H. Cross section of the pyrene; I. Dorsal face of the pyrene; J. Lateral surface of the pyrene; K. Ventral face of the pyrene. Drawn by Michèle Magat.

FIGURE 7 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 7. Psychotria nigotei Barrabé. A. Habit; B. Young fruits; C. Flowers at anthesis. Photos credits: Céline Grignon (B); Frédéric Rigault (A, C).

FIGURE 3 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 3. Distribution map of the four new Psychotria species in New Caledonia. Ultramafic substrates are shaded in gray.

FIGURE 5 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 5. Psychotria ireneae Barrabé. A. Habit; B. Flower at anthesis; C. Young fruit; D. Mature fruits. Photos by Laure Barrabé (A, B, C); Daniel & Irène Létocart (D).

FIGURE 4 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 4. Psychotria ireneae Barrabé. A. Branches with inflorescences and a young fruit; B. Detail of an inflorescence with a flower at anthesis; C. Stipule; D. Young fruit; E. Dorsal face of the pyrene; F. Ventral face of the pyrene; G. Cross section of the pyrene. Drawn by Michèle Magat.

FIGURE 2 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 2. Psychotria fambartiae Barrabé. A. Habit; B. Flowers at anthesis. Photos credits: Hervé Vandrot.

FIGURE 1 in Four new species of Psychotria (Rubiaceae) from New Caledonia, including one presumed to be extinct

FIGURE 1. Psychotria fambartiae Barrabé. A. Branches with inflorescences and young fruits; B. Detail of the abaxial leaf apex; C. Stipule; D. Detail of an inflorescence with flowers at anthesis; E. Young fruit; F. Dorsal face of the pyrene; G. Ventral face of the pyrene; H. Lateral surface of the pyrene; I. Cross section of the pyrene. Drawn by Michèle Magat.

opencc-zeroAug 2021View details →

Data for: Environmental and anthropogenic constraints on animal space use drive extinction risk worldwide

Animals require a certain amount of habitat to persist and thrive, and habitat loss is one of the most critical drivers of global biodiversity decline. While habitat requirements have been predicted by relationships between species traits and home range size, little is known about constraints imposed by environmental conditions and human impacts on a global scale. Our meta-analysis of 395 vertebrate species shows that global climate gradients in temperature and precipitation exert indirect effects via primary productivity, generally reducing space requirements. Human pressure, however, reduces realized space use due to ensuing limitations in available habitat, particularly for large carnivores. We show that human pressure drives extinction risk by increasing the mismatch between space requirements and availability. We use large-scale climate gradients to predict current species extinction risk across global regions, which also offers an important tool for predicting future extinction risk due to ongoing space loss and climate change.

opencc-zeroAug 2021View details →

Data for: The role of habitat fragmentation in Pleistocene megafauna extinction in Eurasia by Mondanaro et al.

This dataset provides the complete list of data and necessary information in order to reproduce all the analyses performed in the paper: "Mondanaro, A., Di Febbraro, M., Melchionna, M., Maiorano, L., Di Marco, M., Edwards, N.R., Holden, P.B., Castiglione, S., Rook, L., Raia, P. (2021) The role of habitat fragmentation in Pleistocene megafauna extinction in Eurasia. Ecography, online version" The idea that than several small, rather than a single large, habitat areas, should hold the highest total species richness (the so-called SLOSS debate) brings into question the importance of habitat fragmentation to extinction risk. SLOSS studies are generally addressed over a short time scale, potentially ignoring the long-term dimension of extinction risk. Here, we provide the first long-term evaluation of the role of habitat fragmentation in species extinction, focusing on 22 large mammal species that lived in Eurasia during the last 200,000 years. By combining species distribution models and landscape pattern analysis, we compared temporal dynamics of habitat spatial structure between extinct and extant species, estimating size, number, and degree of geographical isolation of their suitable habitat patches. Our results evidenced that extinct mammals went through considerable habitat fragmentation during the last glacial period and started to fare worse than extant species from about 50 ka. In particular, our modelling effort constrains the fragmentation of habitats into a narrow time window, from 46 to 36 kilo years ago, surprisingly coinciding with known extinction dates of several megafauna species. Landscape spatial structure was the second most important driver affecting megafauna extinction risk (ca. 38% importance), after body mass (ca. 39%) and followed by dietary preferences (ca. 20%). Our results indicate a major role played by landscape fragmentation on extinction. Such evidence provides insights on what might likely happen in the future, with climate change, habitat loss, and fragmentation acting as the main forces exerting their negative effects on biodiversity.