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 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.

Abstract The Late Campanian-aged Kaiparowits Formation (72.5–76.6 Ma) is a thick, fossiliferous fluvio-overbank–lacustrine complex deposited in south-central Utah. Host to one of the richest, most diverse Campanian terrestrial fossil records in North America, the physical environment of the Kaiparowits ecosystem, particularly the dynamics of the hydrological system, remains obscure. In 2014, an extensive bonebed was found in a conglomeratic sandstone unit of fluvial origin, known as the Rainbows and Unicorns Quarry. Isotopic compositions of serially sampled tooth enamel phosphate (δ 18 O p ) from tyrannosaur teeth were analysed to see if they held data that could clarify the palaeohydrology of the Kaiparowits Formation. To assess a greater palaeoecological context for the tyrannosaurs, the isotopic composition of their teeth was compared to other faunal elements, including the giant alligatoroid Deinosuchus , and turtles (Baenid, Gilmoremys , Neurankylus and Trionychid) from the same quarry. The δ 18 O w calculated from tyrannosaur was low, suggesting that isotopically-light, high-altitude runoff strongly influenced the local hydrology of the Kaiparowtis Formation. The seasonal change in δ 18 O of tyrannosaur drinking water ranged from −21.0 to −14.4‰ V-SMOW, while δ 18 O w calculated from turtles and crocodiles ranged between an average of −9.3 and −10.9‰, respectively. The seasonal precipitation pattern and temperature of the Kaiparowits Formation was then compared to analogue settings, such as the monsoonal climate of Hanoi, Vietnam and Cuiaba, Brazil. While similarities exist between these sites, the unique configuration of the Sevier Mountains adjacent to the nearby Western Interior Seaway provides the unique setting for a complex palaeohydrological system that results in a wide range of δ 18 O w as a result of cold seasonal precipitation at high elevation that runs off and mixes with local precipitation (−6.0 to −4.68‰) sourced from the Western Interior Seaway. This study demonstrates the importance of serial- and micro-sampling of multi-taxa comparisons for isotopic investigations of palaeohydrological systems.

Abstract New Caledonia is known as a global biodiversity hotspot. Like most Pacific islands, its modern biota is characterized by high levels of endemism and is notably lacking in some functional groups of biota. This is the result of its distinctive palaeobiogeographical history, which can be described in terms of three major episodes relating to Gondwana, Zealandia and New Caledonia. The geological record, the fossil record and the modern biota of the archipelago are all reviewed here. The geological record shows that the main island, Grande Terre, was submerged between 75 and 60 Ma. There is a 9 myr interval without any geological record between 34 and 25 Ma, immediately after the obduction of the Peridotite Nappe. Grande Terre may or may not have been submerged during this 9 myr interval. The ages given by molecular biology, independent of any geological calibration points, form a continuous spectrum from 60 Ma up to the present day. The derived lineage ages from molecular phylogenies all post-date 60 Ma, supporting the idea of the continuous availability of terrestrial environments since 60 Ma. Of the three common scenarios for the origin of the New Caledonia biota, long-distance dispersal is the most plausible, rather than vicariance or dispersal over short distances.

ABSTRACT There are two fossil records: the physical fossil record , which consists of specimens, and the abstracted fossil record , which is made up of data derived from those specimens. Mseum collections are the conduit between these two fossil records. Over the past several decades, the abstracted fossil record has provided many important insights about the major features of life’s history, but it has relied mostly on limited types of data (primarily taxonomic occurrence data) derived from ultimately finite literature sources. In contrast, specimen collections and modern tools for digitizing information about them present an opportunity to transform paleobiology into a “big data” science. Digitally capturing non-traditional (e.g., paleoecological, taphonomic, geochemical, and morphological) data from millions of specimens in museum collections and then integrating them with other unique big data resources has the potential to lead to the most important paleontological discoveries of the twenty-first century. What we know about the past record relied heavily on museum collections—the cumulation of centuries of investigation of the fossil record. The sample of past biodiversity will accumulate only with continued exploration of the fossil record … and restudy of existing collections…. —J. Sepkoski (1992, p. 80)