Ediacaran fronds are key components of terminal-Proterozoic ecosystems. They represent one of the most widespread and common body forms ranging across all major Ediacaran fossil localities and time slices postdating the Gaskiers glaciation, but uncertainty over their phylogenetic affinities has led to uncertainty over issues of homology and functional morphology between and within organisms displaying this ecomorphology. Here we present the first large-scale, multigroup cladistic analysis of Ediacaran organisms, sampling 20 ingroup taxa with previously asserted affinities to the Arboreomorpha, Erniettomorpha, and Rangeomorpha. Using a newly derived morphological character matrix that incorporates multiple axes of potential phylogenetically informative data, including architectural, developmental, and structural qualities, we seek to illuminate the evolutionary history of these organisms. We find strong support for existing classification schema and devise apomorphy-based definitions for each of the three frondose clades examined here. Through a rigorous cladistic framework it is possible to discern the pattern of evolution within and between these clades, including the identification of homoplasies and functional constraints. This work both validates earlier studies of Ediacaran groups and accentuates instances in which previous assumptions of their natural history are uninformative.

Extant species of the genus Equus (e.g., horses, asses, and zebras) have a widespread distribution today on all continents except Antarctica. Extinct species of Equus represented by fossils were likewise widely distributed in the Pliocene and even more so during the Pleistocene. In order to understand the efficacy of “big data” for (paleo)biogeographic analyses, location records (latitude, longitude) and fossil occurrences for the genus Equus were mined and further explored from six databases, including iDigBio, Paleobiology Database, VertNet, BISON, Neotoma, and GBIF. These were chosen from a priori knowledge of where relevant data might be aggregated. We also realized that these databases have different objectives and data sources and therefore would provide a useful comparative study of the widespread taxon Equus in space and time.

The mining of Equus data from these six sources yielded a combined total of 123.8 K location records, including 116.2K fossil specimens. These include individual points that are unique, that is, only occurring in one of these databases, and those that are duplicated in multiple databases. Of the six databases, three (iDigBio, Paleobiology Database, and GBIF) were judged to be the most useful in the Equus use case. Most of the databases are biased toward North American records, thus limiting the reconstruction of the actual distribution of the genus Equus in space and time outside of this continent. Although Equus has a large number of digitally accessible records, fundamentally interesting questions pertaining to evolutionary dynamics and extinction geography are still a challenge for these kinds of biodiversity databases due primarily to the lack of sufficiently dense and precise temporal data.

There is a well-established discrepancy between paleontological and molecular data regarding the timing of the origin and diversification of placental mammals. Molecular estimates place interordinal diversification dates in the Cretaceous, while no unambiguous crown placental fossils have been found prior to the end-Cretaceous mass extinction. Here, the completeness of the eutherian fossil record through geological time is evaluated to assess the suggestion that a poor fossil record is largely responsible for the difference in estimates of placental origins. The completeness of fossil specimens was measured using the character completeness metric, which quantifies the completeness of fossil taxa as the percentage of phylogenetic characters available to be scored for any given taxon. Our data set comprised 33 published cladistic matrices representing 445 genera, of which 333 were coded at the species level.

There was no significant difference in eutherian completeness across the Cretaceous/Paleogene (K/Pg) boundary. This suggests that the lack of placental mammal fossils in the Cretaceous is not due to a poor fossil record but more likely represents a genuine absence of placental mammals in the Cretaceous. This result supports the “explosive model” of early placental evolution, whereby placental mammals originated around the time of the K/Pg boundary and diversified soon after.

No correlation was found between the completeness pattern observed in this study and those of previous completeness studies on birds and sauropodomorph dinosaurs, suggesting that different factors affect the preservation of these groups. No correlations were found with various isotope proxy measures, but Akaike information criterion analysis found that eutherian character completeness metric scores were best explained by models involving the marine-carbonate strontium-isotope ratios (87Sr/86Sr), suggesting that tectonic activity might play a role in controlling the completeness of the eutherian fossil record.

Biodiversity hotspots are increasingly recognized as areas of high taxonomic and functional diversity. These hotspots are dynamic and shift geographically over time in response to environmental change. To identify drivers of the origin, evolution, and persistence of diversity hotspots, we investigated the diversity patterns of reef-building corals (Scleractinia) in the Central Indo-Pacific, a marine biodiversity hotspot for the last 25 Myr. We used the scleractinian fossil record (based on literature and a newly acquired fossil collection) to examine the taxonomic and functional diversity of corals from the Eocene to Pliocene. Our data identify potential drivers of coral diversity through time (and space) in the Central Indo-Pacific by constraining the timing of taxonomic turnover events and correlating them with known environmental changes. Increases in taxonomic diversity, high origination rates, and changes in abundance of functional character states indicate that the origin of the Central Indo-Pacific hotspot occurred during the Oligocene, initially through proliferation of pre-existing taxa and then by origination of new taxa. In contrast to taxonomic diversity, overall functional diversity of Central Indo-Pacific reef-building corals remained constant from the Eocene to the Pliocene. Our results identify global sea level as a main driver of diversity increase that, together with local tectonics, regulates availability of suitable habitats. Moreover, marine biodiversity hotspots develop from both the accumulation of taxa from older biodiversity hotspots and origination of new taxa. Our study demonstrates the utility of a combined literature-based and new collection approach for gaining new insights into the timing, drivers, and development of tropical biodiversity hotspots.

Throughout the late Quaternary, the Sahul (Pleistocene Australia–New Guinea) vertebrate fauna was dominated by a diversity of large mammals, birds, and reptiles, commonly referred to as megafauna. Since ca. 450–400Ka, approximately 88 species disappeared in Sahul, including kangaroos exceeding 200kg in size, wombat-like animals the size of hippopotamuses, flightless birds, and giant monitor lizards that were likely venomous. Ongoing debates over the primary cause of these extinctions have typically favored climate change or human activities. Improving our understanding of the population biology of extinct megafauna as more refined paleoenvironmental data sets become available will assist in identifying their potential vulnerabilities. Here, we apply a multiproxy approach to analyze fossil teeth from deposits dated to the middle and late Pleistocene at Cuddie Springs in southeastern Australia, assessing relative aridity via oxygen isotopes as well as vegetation and megafaunal diets using both carbon isotopes and dental microwear texture analyses. We report that the Cuddie Springs middle Pleistocene fauna was largely dominated by browsers, including consumers of C4 shrubs, but that by late Pleistocene times the C4 dietary component was markedly reduced. Our results suggest dietary restriction in more arid conditions. These dietary shifts are consistent with other independently derived isotopic data from eggshells and wombat teeth that also suggest a reduction in C4 vegetation after ~45 Ka in southeastern Australia, coincident with increasing aridification through the middle to late Pleistocene. Understanding the ecology of extinct species is important in clarifying the primary drivers of faunal extinction in Sahul. The results presented here highlight the potential impacts of aridification on marsupial megafauna. The trend to increasingly arid conditions through the middle to late Pleistocene (as identified in other paleoenvironmental records and now also observed, in part, in the Cuddie Springs sequence) may have stressed the most vulnerable animals, perhaps accelerating the decline of late Pleistocene megafauna in Australia.

Morphological responses of nonmammalian herbivores to external ecological drivers have not been quantified over extended timescales. Herbivorous nonavian dinosaurs are an ideal group to test for such responses, because they dominated terrestrial ecosystems for more than 155 Myr and included the largest herbivores that ever existed. The radiation of dinosaurs was punctuated by several ecologically important events, including extinctions at the Triassic/Jurassic (Tr/J) and Jurassic/Cretaceous (J/K) boundaries, the decline of cycadophytes, and the origin of angiosperms, all of which may have had profound consequences for herbivore communities. Here we present the first analysis of morphological and biomechanical disparity for sauropodomorph and ornithischian dinosaurs in order to investigate patterns of jaw shape and function through time. We find that morphological and biomechanical mandibular disparity are decoupled: mandibular shape disparity follows taxonomic diversity, with a steady increase through the Mesozoic. By contrast, biomechanical disparity builds to a peak in the Late Jurassic that corresponds to increased functional variation among sauropods. The reduction in biomechanical disparity following this peak coincides with the J/K extinction, the associated loss of sauropod and stegosaur diversity, and the decline of cycadophytes. We find no specific correspondence between biomechanical disparity and the proliferation of angiosperms. Continual ecological and functional replacement of pre-existing taxa accounts for disparity patterns through much of the Cretaceous, with the exception of several unique groups, such as psittacosaurids that are never replaced in their biomechanical or morphological profiles.

Whether the evolutionary dynamics of one group of organisms influence that of another group of organisms over the vast timescale of the geological record is a difficult question to tackle. This is not least because multiple factors can influence or mask the effects of potential driving forces on evolutionary dynamics of the focal group. Here, we show how an approach amenable to causality inference for time series, linear stochastic differential equations (SDEs), can be used in a multivariate fashion to shed light on driving forces of diversification dynamics across the Phanerozoic. Using a new, enhanced stepwise search algorithm, we searched through hundreds of models to converge on a model that best describes the dynamic relationships that drove brachiopod and bivalve diversification rates. Using this multivariate framework, we characterized a slow process (half-life of c. 42 Myr) that drove brachiopod extinction. This slow process has yet to be identified from the geological record. Using our new framework for analyzing multiple linear SDEs, we also corroborate our previous findings that bivalve extinction drove brachiopod origination in the sense that brachiopods tended to diversify at a greater rate when bivalves were removed from the system. It is also very likely that bivalves “self-regulate” in the sense that bivalve extinctions also paved the way for higher bivalve origination rates. Multivariate linear SDEs as we presented them here are likely useful for studying other dynamic systems whose signatures are preserved in the paleontological record.

One of the longest-lived, noncolonial animals on the planet today is a bivalve that attains life spans in excess of 500 years and lives in a cold, seasonally food-limited setting. Separating the influence of temperature and food availability on life span in modern settings is difficult, as these two conditions covary. The life spans of fossil animals can provide insights into the role of environment in the evolution of extreme longevity that are not available from studies of modern taxa. We examine bivalves from the unique, nonanalogue, warm and high-latitude setting of Seymour Island, Antarctica, during the greenhouse intervals of the Late Cretaceous and Paleogene. Despite significant sampling limitations, we find that all 11 species examined are both slow growing and long-lived, especially when compared with modern bivalves living in similar temperature settings. While cool temperatures have long been thought to be a key factor in promoting longevity, our findings suggest an important role for caloric restriction brought about by the low and seasonal light regime of the high latitudes. Our life-history data, spanning three different families, emphasize that longevity is in part governed by environmental rather than solely phylogenetic or ecologic factors. Such findings have implications for both modern and ancient latitudinal diversity gradients, as a common correlate of slow growth and long life is delayed reproduction, which limits the potential for evolutionary change. While life spans of modern bivalves are well studied, data on life spans of fossil bivalves are sparse and largely anecdotal. Life histories of organisms from deep time can not only elucidate the controls on life span but also add a new dimension to our understanding of macroevolutionary patterns.

Extensive investigation of the close association between biological diversity and environmental temperature has not yet yielded a generally accepted, empirically validated mechanism to explain latitudinal gradients of species diversity, which occur in most taxa. Using the highly resolved late Cenozoic fossil records of four major taxa of marine plankton, we show that their gradients arise as a consequence of asymmetric geographic range expansion rather than latitudinal variation in diversification rate, as commonly believed. Neither per capita speciation nor extinction rates trend significantly with temperature or latitude for these marine plankton. Species of planktonic foraminifera and calcareous nannoplankton that originate in the temperate zone preferentially spread toward and arrive earlier in the tropics to produce a normal gradient with tropical diversity peaks; by contrast, temperate-zone originating species of diatoms and radiolarians preferentially spread toward and arrive earlier in polar regions to produce reversed gradients with high-latitude diversity peaks. Our results suggest that temperature affects latitudinal diversity gradients chiefly by its effect on species’ range limits rather than on probabilities of speciation and extinction. We show that this mechanism also appears to operate in various multicellular taxa, thus providing a widely applicable explanation for the origin of latitudinal diversity gradients.

Recent studies of eurypterid paleoecology suggest that formation of eurypterid Lagerstätten in the mid-Paleozoic of Laurentia was controlled by the presence of an ecological–taphonomic window that recurred predictably in nearshore, marginal environments during transgressions. We tested this hypothesis by performing a high-resolution taxonomic, environmental, and stratigraphic survey and quantitative analysis of all Silurian–Lower Devonian eurypterid-bearing intervals in the Appalachian basin, the most prolific region for eurypterid remains in the world. Canonical correspondence analysis of sedimentological and faunal associations revealed a strong lithologic gradient between groupings of eurypterid genera and associated taxa across the basin, and a significant association of eurypterids with microbialites (thrombolites, stromatolites) and evaporitic structures. Field observations confirmed that, stratigraphically, eurypterids in the basin frequently occur above the microbialite structures and beneath evaporites and other indicators of increased salinity or subaerial exposure. Following interpretation of these features within a sequence stratigraphic framework, we present a preservational model in which (1) eurypterids inhabited nearshore settings following freshening conditions concomitant with minor transgressions, (2) their remains were subsequently buried by storms or microbialite sediment baffling, and (3) subsequent long-term preservation of tissues was facilitated by regression and cyclical shallowing-up successions that promoted hypersalinity and anoxia. In the central and southern region of the basin, where microbial structures and evidence for hypersalinity are less common, a similar pattern of cyclical shallowing-upward deposition within eurypterid-bearing units holds. Thus, eurypterid preservation appears to reflect a combination of ecological preferences and abiotic conditions that promoted inhabitation and eventual preservation within the same setting. This study provides the first quantitative support for a sea level–based control on preservation of eurypterids and adds to the growing body of evidence that suggests that analysis of exceptional preservation in the fossil record benefits from interpretation within a sequence stratigraphic framework.

As a label for a distinct category of life, “living fossil” is controversial. The term has multiple definitions, and it is unclear whether the label can be genuinely used to delimit biodiversity. Even taking a purely phylogenetic perspective in which a proxy for the living fossil is evolutionary distinctness (ED), an inconsistency arises: Does it refer to “dead-end” lineages doomed to extinction or “panchronic” lineages that survive through multiple epochs? Recent tree-growth model studies indicate that speciation rates must have been unequally distributed among species in the past to produce the shape of the tree of life. Although an uneven distribution of speciation rates may create the possibility for a distinct group of living fossil lineages, such a grouping could only be considered genuine if extinction rates also show a consistent pattern, be it indicative of dead-end or panchronic lineages. To determine whether extinction rates also show an unequal distribution, we developed a tree-growth model in which the probability of speciation and extinction is a function of a tip’s ED. We simulated thousands of trees in which the ED function for a tip is randomly and independently determined for speciation and extinction rates. We find that simulations in which the most evolutionarily distinct tips have lower rates of speciation and extinction produce phylogenetic trees closest in shape to empirical trees. This implies that a distinct set of lineages with reduced rates of diversification, indicative of a panchronic definition, is required to create the shape of the tree of life.

In this study we focused on the dynamics of encrusting assemblages preserved on brachiopod hosts collected from upper Frasnian and lower Famennian deposits of the Central Devonian Field, Russia. Because the encrusted brachiopods come from deposits bracketing the Frasnian/Famennian (F/F) boundary, the results also shed some light on ecological differences in encrusting communities before and after the Frasnian–Famennian (F-F) event. To explore the diversity dynamics of encrusting assemblages, we analyzed more than 1300 brachiopod valves (substrates) from two localities. Taxon accumulation plots and shareholder quorum subsampling (SQS) routines indicated that a reasonably small sample of brachiopod host valves (n=50) is sufficient to capture the majority of the encrusting genera recorded at a given site. The richness of encrusters per substrate declined simultaneously with the number of encrusting taxa in the lower Famennian, accompanied by a decrease in epibiont abundance, with a comparable decrease in mean encrustation intensity (percentage of bioclasts encrusted by one or more epibionts). Epibiont abundance and occupancy roughly mirror each other. Strikingly, few ecological characteristics are correlated with substrate size, possibly reflecting random settlement of larvae. Evenness, which is negatively correlated with substrate size, shows greater within-stage variability among samples than between Frasnian and Famennian intervals and may indicate the instability of early Famennian biocenoses following the faunal turnover. The occurrence distribution of encrusters points to nonrandom associations and exclusions among several encrusting taxa. However, abundance and occupancy of microconchids remained relatively stable throughout the sampled time interval. The notable decline in abundance (~60%) and relatively minor decline in diversity (~30%) suggest jointly that encrusting communities experienced ecological collapse rather than a major mass extinction event. The differences between the upper Frasnian and lower Famennian encrusting assemblages may thus record a turnover associated with the F-F event.

Understanding the drivers of macroevolutionary trends through the Phanerozoic has been a central question in paleobiology. Increasingly important is understanding the regional and environmental variation of macroevolutionary patterns and how they are reflected at the global scale. Here we test the role of biotic interactions on regional ecological patterns during the Mesozoic marine revolution. We test for escalatory trends in Jurassic marine benthic macroinvertebrate ecosystems using occurrence data from the Paleobiology Database parsed by region and environment. The escalation hypothesis posits that taxonomic groups that could adapt to intense predation and bioturbation proliferated, whereas groups unable to adapt were reduced in diversity and abundance or driven to extinction. We tested this hypothesis in five regions during Jurassic stages and among four depositional environments in Europe. Few escalatory trends were detected, although at least one escalatory trend was observed in every region, with the greatest number and strongest trends observed in Europe. These trends include increases in shallow infauna and cementing epifauna and occurrences of facultatively mobile invertebrates and decreases in pedunculate, free-lying, and sessile epifauna. Within Europe, escalatory trends occur in shallow-water environments but also in deeper-water environments, where they are predicted not to occur. When regional trends are aggregated, trends in Europe drive the global signal. The results of this study suggest that while evidence of escalation is rare globally, it is plausible that escalation drove macroevolutionary patterns in Europe. Furthermore, these results underline the need to dissect global fossil data at the regional scale to understand global macroevolutionary dynamics.

Sexual dimorphism is thought to have evolved via selection on both sexes. Ostracodes display sexual shape dimorphism in adult valves; however, no previous studies have addressed temporal changes on evolutionary timescales or examined the relationships between sexual shape dimorphism and selection pressure and between sexual shape dimorphism and juvenile shape. Temporal changes in sexually dimorphic traits result from responses of these traits to selection pressure. Using the Gaussian mixture model for the height/length ratio, a valve-shape parameter, we identified sexual differences in the valve shape of Krithe dolichodeira s.l. from deep-sea sediments of the Paleocene (62.6–57.6 Ma) and estimated the proportion of females in the fossil populations at 11 time intervals. Because the proportion of females in a population is altered by the mortality rate of adult males, it is reflective of selection pressure on males. We attempted to correlate the height/length ratios between the sexes with the proportion of females, taking into consideration that the valve shape was not linked with the selection pressure on males. In time-series data of the height/length ratio, both sexes indicate no significant changes on evolutionary timescales, even though the sex ratio of the population changed from female skewed to male skewed during the late Paleocene. The sexual shape dimorphism was not driven by sexual selection. The static allometry between the height/length ratio and length indicates that the sexual shape dimorphism did not function for sexual display. The absence of change over time in the female allometric slope suggests that the evolution of valve shape was constrained by stasis.

We investigate the association between geographic range and survival in Mesozoic marine animal genera. Previous work using data from the Paleobiology Database (paleobiodb.org) demonstrated greater survivorship overall among Phanerozoic genera that were widespread during their stage of first appearance, but this relationship did not hold during the Mesozoic. To explore this unexpected result, we consider geographic range in conjunction with temporal variation in survival and variation in survival among higher taxa. Because average range and average survival are negatively correlated among stages, for reasons that are still unclear, and because the data are heavily influenced by cephalopods, which include many wide-ranging and short-lived genera, the effect of geographic range on survival is obscured in the aggregate data. Thus, range is not a significant predictor of survival when data are analyzed in aggregate, but it does have a significant effect when variation in average range and average survival among stages and classes is taken into account. The best-fitting models combine range with both temporal and taxonomic heterogeneity as predictive factors. Moreover, when we take stage-to-stage variation into account, geographic range is an important predictor of survival within most classes. Cephalopod genera must be more widespread than genera in other classes for geographic range to significantly increase odds of survival, and factoring in survival heterogeneity of superfamilies further increases model fit, demonstrating a nested nature in the sensitivity of range and taxonomic aggregation.

Reconstructing the tree of life involves more than identifying relationships among lineages; it also entails accurately estimating when lineages diverged. Paleontologists typically scale cladograms to time a posteriori by direct reference to first appearances of taxa in the stratigraphic record. Some approaches use probabilistic models of branching, extinction, and sampling processes to date samples of trees, such as the recently developed cal3 method, which stochastically draws divergence dates given a set of rates for those processes. However, these models require estimates of the rates of those processes, which may be hard to obtain, particularly for sampling. Here, we contrast the use of cal3 and other a posteriori time-scaling approaches by examining a previous study that documented a decelerating rate of morphological evolution in pterocephaliid trilobites. Although aspects of the data set make estimation of branching, extinction, and sampling rates difficult, we use a multifaceted approach to calculate and evaluate the rate estimates needed for applying cal3. In agreement with previous simulation studies, we find that the choice of phylogenetic dating method impacts downstream macroevolutionary conclusions. We also find contradictory evolutionary inferences between analyses on ancestor–descendant contrasts (based on ancestor trait reconstruction methods) and maximum-likelihood parameter estimates. Ancestral taxon inference in cal3 corroborates previously hypothesized ancestor–descendant sequences, but cal3 suggests greater support for budding cladogenesis than anagenesis. This case study demonstrates the potential and wide applicability of the cal3 method and the benefits afforded by choosing cal3 over simpler a posteriori time-scaling approaches.

A priori choices in the detail and breadth of a study are important in addressing scientific hypotheses. In particular, choices in the number and type of characters can greatly influence the results in studies of morphological diversity. A new character suite was constructed to examine trends in the disparity of early Paleozoic crinoids. Character-based rarefaction analysis indicated that a small subset of these characters (~20% of the complete data set) could be used to capture most of the properties of the entire data set in analyses of crinoids as a whole, noncamerate crinoids, and to a lesser extent camerate crinoids. This pattern may be the result of the covariance between characters and the characterization of rare morphologies that are not represented in the primary axes in morphospace. Shifting emphasis on different body regions (oral system, calyx, periproct system, and pelma) also influenced estimates of relative disparity between subclasses of crinoids. Given these results, morphological studies should include a pilot analysis to better examine the amount and type of data needed to address specific scientific hypotheses.

Insects in the fossil record are generally preserved in lacustrine shales or in amber. For those in lacustrine shales, preservation is usually via keroginization or mineralization. Given the extended period of microbial decay required to generate ions for mineralization, there is a predicted inherent bias toward lower preservation quality for this pathway by most taphonomic indices compared with keroginization. This study tests this hypothesis by comparing multiple measures of preservation quality between sites with similar sedimentology in the Eocene Green River Formation of Colorado. Here, insects are either mineralized in iron oxides (likely after pyrite) at the Paleoburn site or keroginized at the Anvil Points site.

Generally, the prediction that keroginization preserves soft-bodied fossils with higher preservational quality than mineralization is affirmed, but with some caveats. Beetles, known for their robust cuticles, are proportionately more abundant at the Paleoburn site, but eight of the nine orders recorded are shared between sites. As predicted, insects show lower preservation fidelity at the Paleoburn site, but they also show higher degrees of disarticulation. This second bias should be acquired primarily during the biostratinomy stage, and not early diagenesis. Nonetheless, higher-energy biostratinomic conditions may be compatible with taphonomic conditions that promote mineralization over keroginization.

Comparing the inherent taphonomic bias of different preservation pathways is often difficult, since fossil deposits may be preserved millions of years or thousands of kilometers apart. By studying two different preservation pathways of insects within the same formation, we can affirm that keroginization does indeed preserve recalcitrant organic matter with higher quality than pyritization or iron-oxide mineralization. Additionally, some guidelines can be proposed concerning the body parts and taxa that can be compared, and for what purpose, when contrasting mineralized and keroginized soft-bodied deposits.

Two end-member models are proposed to explain marine biotic responses to greenhouse conditions. Global warming and increasing sea level may: (1) promote dispersal of marine species, leading to larger geographic ranges and decreased speciation and biodiversity; or (2) result in formation of isolated epicontinental basins that host endemic radiations, leading to smaller geographic ranges and increased speciation and biodiversity. The Cenomanian–Turonian (C–T) interval, marked by greenhouse warming, sea-level rise, ocean anoxia, and biotic turnover, presents an opportunity to test these two end-member models. In particular, how cephalopods responded to these global changes has not been clear. A global database of 7262 cephalopod occurrences was used to evaluate biodiversity changes through the C–T interval. Both species- and genus-level diversity peaked in the late Cenomanian. The global diversity drop across the C/T boundary was modest; rather, diversity was low during the middle Cenomanian and middle Turonian, times of brief cooling. Regional variations in diversity responses may reflect the degree and timing of environmental perturbations within different oceanographic settings. Surprisingly, cephalopod faunas in the European Platform, Western Interior, and South Atlantic all shifted equatorward across the C/T boundary, whereas other regions saw no change in latitudinal distributions. Global generic geographic ranges did not change through the C–T interval, but the percentage of cosmopolitan genera did increase significantly across the C/T, both globally and within the Western Interior and Europe, whereas cosmopolitans dropped in the Pacific and South Atlantic. Neither end-member model for biodiversity change in a greenhouse world is supported for C–T cephalopods, as diversity increased without an associated increase in geographic range. It may be that sea-level rise and global warming led to both endemic radiations in epicontinental basins and an increase in cosmopolitan taxa in some regions, demonstrating the importance of combining global and regional-scale analyses.

A submarine cave is a unique environment that is dark, food limited, semi-isolated from the outside, and sheltered from wave action. However, our knowledge of the long-term change in submarine-cave ecosystems remains limited. We document here the community-scale responses toward long-term change in a submarine cave, Daidokutsu in Okinawa in southern Japan. Using both metazoans (ostracods and bivalves) and protozoans (larger benthic foraminiferans) in two sediment cores obtained from the cave, we reconstruct the faunal and diversity changes of the past 7 Kyr. All taxonomic groups showed long-term, gradual linear change of faunal composition from predominantly open-water taxa to predominantly cave taxa, and ostracods showed short-term variability of species diversity. The long-term faunal trend probably reflects gradual isolation of the cave ecosystem due to coral reef development (i.e., development of the cave ceiling) during periods of the Holocene transgression and subsequent sea-level highstand. The short-term diversity changes show substantial similarity to centennial- to millennial-scale Holocene Asian monsoon variability. Ostracod species diversity peaks tend to correspond with periods of strong East Asian winter monsoons. The results indicate that limestone submarine-cave ecosystems, an important cryptic habitat, developed gradually during the Holocene and may be sensitive to rapid climate changes.