Abstract Conservation palaeobiology informs conservation and restoration of ecosystems by using the fossil record to discriminate between baseline and novel states and to assess ecosystem response to perturbations. Variability in the time-scale of palaeobiological data can generate patterns that either exaggerate or mute the magnitude of biotic changes. We identify two approaches that remedy the challenges associated with the mixing of baseline and post-impact states and with the transformation of the stratigraphic depth to time. First, combining surface death assemblages with both (1) fossil assemblages preserved in the subsurface historical layers and (2) living assemblages can better resolve the nature of ecosystem shifts than within-core surveys or live–dead analyses alone. Second, post-mortem age distributions of skeletal particles and their preservation states are not only informative about stratigraphic resolution and time averaging of death assemblages but also about the timing of changes in abundance of skeletal producers. High abundance of the youngest age cohorts in surface death assemblages is a null expectation of disintegration and burial dynamic. When this dynamic is accounted for, age distributions of benthic invertebrates from Holocene sediments often reveal high volatility, prolonged turn-offs in production or pervasive regime shifts that are obscured in the raw stratigraphic record.

ABSTRACT Ediacaran sediments record the termination of Cryogenian “snowball Earth” glaciations, preserve the first occurrences of macroscopic metazoans, and contain one of the largest known negative δ 13 C excursions (the Shuram-Wonoka). The rock record for the transition between the Proterozoic and Phanerozoic in North America is also physically distinct, with much of the continent characterized by a wide variety of mostly crystalline Proterozoic and Archean rocks overlain by Lower Paleozoic shallow-marine sediments. Here, we present quantitative macrostratigraphic summaries of rock quantity and type using a new comprehensive compilation of Ediacaran geological successions in North America. In keeping with previous results that have identified early Paleozoic burial of the “Great Unconformity” as a major transition in the rock record, we find that the Ediacaran System has greatly reduced areal extent and volume in comparison to the Cambrian and most younger Phanerozoic systems. The closest quantitative analogue to the Ediacaran System in North America is the Permian–Triassic interval, deposited during the culminating assembly and early rifting phases of the supercontinent Pangea. The Shuram-Wonoka carbon isotope excursion occurs against the backdrop of the largest increase in carbonate and total rock volume observed in the Ediacaran. The putatively global Gaskiers glaciation (ca. 580–579 Ma), by contrast, has little quantitative expression in these data. Although the importance of Ediacaran time is often framed in the context of glaciation, biological evolution, and geochemical perturbations, the quantitative expressions of rock area, volume, and lithology in the geologic record clearly demark the late Ediacaran to early Cambrian as the most dramatic transition in at least the past 635 m.y. The extent to which the timing and nature of this transition are reflected globally remains to be determined, but we hypothesize that the large expansion in the extent and volume of sedimentation within the Ediacaran, particularly among carbonates, and again from the Ediacaran to the Cambrian, documented here over ~17% of Earth’s present-day continental area, provides important insights into the drivers of biogeochemical and biological evolution at the dawn of animal life.

Abstract Studies of Triassic insects in China began in 1956, and, so far, a total of 89 genera and 109 species have been found from the Triassic of China. The fossil records from 17 provinces (or regions) in China are assigned to 11 orders, except for two genera and species considered incertae sedis in Insecta. These Chinese Triassic insects, including one Early Triassic, 53 Middle Triassic and 55 Late Triassic species, are briefly reviewed in taxonomy and distribution, and listed here with detailed taxonomic and stratigraphic information. The Middle Triassic Tongchuan and Late Triassic Toksun entomofaunas are introduced in detail from the perspectives of composition and taxonomy. Existing data indicate that the Chinese Triassic entomofauna is dominated by Hemiptera, Mecoptera and Coleoptera; the Chinese Early Triassic insects are only known from Fuyuan in Yunnan Province, Middle Triassic insects are mainly known from northern China and sporadically from Guizhou Province, southern China, and Late Triassic insects are seen widely in both northern and southern China. The Middle and Late Triassic entomofaunas have a similar abundance but show a pattern of being more common in northern China than in southern China.

Abstract True hoppers, consisting of Fulgoromorpha and Cicadomorpha, are plant feeders with very high species-level diversity. A large number of true hopper fossils have been reported from eastern Asia, especially from the Middle to Late Jurassic Yanliao Biota, the Early Cretaceous Jehol Biota and mid-Cretaceous Kachin amber in the last two decades. Herein, true hoppers from the Jurassic and Cretaceous of eastern Asia are reviewed, and combining palaeontological data from other regions of the world and recent advances of molecular studies, the evolutionary history of true hoppers in the mid–late Mesozoic is discussed. Permocicada beipiaoensis Wang, 1987 and Archijassus plurinervis Zhang, 1985 are here excluded from Prosboloidea and Archijassidae, respectively. By the end of 2020, a total of 203 species with definite systematic position had been documented in the Jurassic and Cretaceous of eastern Asia (China, Myanmar, Siberia, Mongolia, Japan and Korea), and were attributed to 116 genera in 22 families and 7 superfamilies. Available fossil data suggest that true hopper components strongly changed in the Cretaceous: primitive groups reduced and went extinct successively, and the origin and/or early diversification of most lineages (family or subfamily level) occurred, likely owing to the displacement of host-plants in the angiosperm floristic revolution.

ABSTRACT More than four decades have passed since Walter Alvarez helped to bring mass extinctions to the attention of a broad audience and inspired extensive multidisciplinary research on a wide variety of topics ranging from the Cretaceous/Paleogene (K/Pg) and other impact events to astronomy, climate modeling, and the centuries-long debate on the extent to which apparent extinctions are a real phenomenon or due to incompleteness of the fossil record. Many questions about ecosystems in the aftermath of extinctions remain, and we summarize knowledge about an integral part of this discussion, i.e., oceanic productivity after the K/Pg mass extinction. We compiled new and published benthic foraminiferal data across the K/Pg boundary globally, at geographically and bathymetrically diverse sites, to contribute to the understanding of environmental consequences of the K/Pg impact through analysis of extinction patterns in Earth’s largest habitat: the deep seafloor. We find no significant links between the severity of extinction of benthic foraminiferal species or their global decrease in diversity and factors such as the distance from the Chicxulub crater, paleo-water depth, and paleolatitude. Benthic foraminiferal populations show strong post-impact variability in space and time, supporting the hypothesis of heterogeneous oceans with extensive, local-to-regional plankton blooms, but we suggest that the apparent geographic variability may at least in part be due to incompleteness of the geological record at high time resolution. Additional high-resolution studies are necessary to enable us to evaluate the rates of past extinctions and compare these to the rates of present and future extinctions.

Abstract Ophiuroids, the slender-armed cousins of starfish, constitute an important component of modern marine benthos and have been used successfully in the exploration of (palaeo)-ecological and evolutionary trends, yet their fossil record is still poorly known. One of the major gaps in the known palaeobiodiversity of this group coincides with a global palaeoenvironmental crisis during the early Toarcian (Early Jurassic, 183 myr ago), known as the Jenkyns Event. Here we describe ophiuroid remains retrieved from a series of samples from the Dudelange (Luxembourg) drill core, which spans the lower part of the Toarcian, between the top of the Pliensbachian and the onset of the Jenkyns Event. A total of 21 species are recorded, including three new genera and 12 new species. Ophiuroid diversity and abundance fluctuate in parallel with depositional facies, with lowest values coinciding with black shales. Highest diversities, including exceptional occurrences of taxa nowadays restricted to deep-sea areas, are recorded from just below the black shales, corresponding to the onset of the Jenkyns Event. Our results show that even small (100 g) bulk sediment samples retrieved from drill cores can yield numerous identifiable ophiuroid remains, thus unlocking this group for the study of faunal change across palaeoenvironmental crises.