The Paleobiology Database (PBDB;  https://paleobiodb.org) consists of geographically and temporally explicit, taxonomically identified fossil occurrence data. The taxonomy utilized by the PBDB is not static, but is instead dynamically generated using an algorithm applied to separately managed taxonomic authority and opinion data. The PBDB owes its existence to many individuals, some of whom have entered more than 1.26 million fossil occurrences and over 570,000 taxonomic opinions, and some of whom have developed and maintained supporting infrastructure and analysis tools. Here, we provide an overview of the data model currently used by the PBDB and then briefly describe how this model is exposed via an Application Programming Interface (API). Our objective is to outline how PBDB data can now be accessed within individual scientific workflows, used to develop independently managed educational and scientific applications, and accessed to forge dynamic, near real-time connections to other data resources.

Hypotheses regarding the evolution of many clades are often generated in the absence of data from the fossil record and potential biases introduced by exclusion of paleontological data are frequently ignored. With regard to body size evolution, extinct taxa are frequently excluded because of the lack of body mass estimates—making identification of reliable clade specific body mass estimators crucial to evaluating trends on paleontological timescales. Herein, I identify optimal osteological dimensions for estimating body mass in extinct species of Pan-Alcidae (Aves, Charadriiformes) and utilize newly generated estimates of body mass to demonstrate that the combination of neontological and paleontological data produces results that conflict with hypotheses generated when extant species data are analyzed in isolation. The wing-propelled diving Pan-Alcidae are an ideal candidate for comparing estimates of body mass evolution based only on extant taxa with estimates generated including fossils because extinct species diversity (≥31 species) exceeds extant diversity, includes examples from every extant genera, and because phylogenetic hypotheses of pan-alcid relationships are not restricted to the 23 extant species. Phylogenetically contextualized estimation of body mass values for extinct pan-alcids facilitated evaluation of broad scale trends in the evolution of pan-alcid body mass and generated new data bearing on the maximum body mass threshold for aerial flight in wing-propelled divers. The range of body mass in Pan-Alcidae is found to exceed that of all other clades of Charadriiformes (shorebirds and allies) and intraclade body mass variability is recognized as a recurring theme in the evolution of the clade. Finally, comparisons of pan-alcid body mass rangewith penguins and the extinct †Plotopteridae elucidate potentially shared constraints among phylogenetically disparate yet ecologically similar clades of wing-propelled divers.

The Tulip Beds locality on Mount Stephen (Yoho National Park, British Columbia) yields one of the most abundant and diverse (∼10,000 specimens in 110 taxa) Burgess Shale fossil assemblages in the Canadian Rockies. Detailed semi quantitative and quantitative analyses of this assemblage suggest strong similarities with the Walcott Quarry on Fossil Ridge. Both assemblages are dominated by epibenthic, sessile, and suspension feeding taxa, mostly represented by arthropods and sponges and have comparable diversity patterns, despite sharing only about half the genera. However, the Tulip Beds has a higher relative abundance of suspension feeders and taxa of unknown affinity compared to the Walcott Quarry. These biotic variations are probably largely attributable to ecological and evolutionary differences between the two temporally distinct communities that adapted to similar, but not identical, environmental settings. For instance, the Tulip Beds is farther away from the Cathedral Escarpment than the Walcott Quarry. The Tulip Beds and Walcott Quarry assemblages are more similar to each other than either one is to the assemblages of the Chengjiang biota, although the relative diversity of major taxonomic groups and ecological patterns are similar in all assemblages. The conserved diversity patterns and ecological structures among sites suggest that the ecological composition of Cambrian Burgess Shale-type communities was relatively stable across wide geographic and temporal scales.

Age-frequency distributions of dead skeletal material on the landscape or seabed—information on the time that has elapsed since the death of individuals—provide decadal- to millennial-scale perspectives both on the history of production and on the processes that lead to skeletal disintegration and burial. So far, however, models quantifying the dynamics of skeletal loss have assumed that skeletal production is constant during time-averaged accumulation. Here, to improve inferences in conservation paleobiology and historical ecology, we evaluate the joint effects of temporally variable production and skeletal loss on postmortem age-frequency distributions (AFDs) to determine how to detect fluctuations in production over the recent past from AFDs. We show that, relative to the true timing of past production pulses, the modes of AFDs will be shifted to younger age cohorts, causing the true age of past pulses to be underestimated. This shift in the apparent timing of a past pulse in production will be stronger where loss rates are high and/or the rate of decline in production is slow; also, a single pulse coupled with a declining loss rate can, under some circumstances, generate a bimodal distribution. We apply these models to death assemblages of the bivalve Nuculana taphria from the Southern California continental shelf, finding that: (1) an onshore-offshore gradient in time averaging is dominated by a gradient in the timing of production, reflecting the tracking of shallow-water habitats under a sea-level rise, rather than by a gradient in disintegration and sequestration rates, which remain constant with water depth; and (2) loss-corrected model-based estimates of the timing of past production are in good agreement with likely past changes in local production based on an independent sea-level curve.

It has generally been argued that the majority of fossil benthic foraminifera, the most common proxy for paleo bottom oceanic conditions, could not tolerate anoxia. Here we present evidence that fossil foraminifera were able to successfully colonize anoxic-dysoxic bottom waters, by using adaptations similar to those found in living species. Our study is based on a multi proxy micropaleontological and geochemical investigation of the Upper Cretaceous sediments from the Levant upwelling regime. A shift from buliminid to diverse trochospiral dominated assemblages was recorded in an interval with a distinct anoxic geochemical signature coinciding with a regional change in lithology. This change was triggered by an alteration in the type of primary producers from diatoms to calcareous nannoplankton, possibly causing modifications in benthic foraminiferal morphological and physiological adaptations to life in the absence of oxygen.

Our data show that massive blooms of triserial (buliminid) benthic foraminifera with distinct apertural and test morphologies during the Campanian were enabled by their ability to sequester diatom chloroplasts and associate with bacteria, in a similar manner as their modern analogs. Diverse trochospiral forms existed during the Maastrichtian by using nitrate instead of oxygen for their respiratory pathways in a denitrifying environment. Species belonging to the Stilostomellidae and Nodosariidae families might have been affected by the change in food type arriving to the seafloor after the phytoplankton turnover at the Campanian/Maastrichtian boundary, in a similar manner as their mid Pleistocene descendants prior to their extinction. This study promotes the need for a re-evaluation of the current models used for interpreting paleoceanographic data and demonstrates that the identification of adaptations and mechanisms involved in promoting sustained life under anoxic to dysoxic conditions should become a standard in faunal paleoceanographic studies.

Dental microwear analyses of ungulates and other large herbivores rely on correlations of diet and microwear among extant ungulates, primarily ruminants. Microwear is considered a ‘taxon-free’ method of paleodietary analysis. The properties of food are associated with causality of microwear, but the possibility that heritable properties of the consumer (tooth morphologies, masticatory dynamics, enamel mechanical properties, digestive physiologies) may introduce bias is not considered. Using an observer blind method of light microscopy, we examined the distribution of microwear features on the molars of eight species of ruminants and perissodactyls. Grazing and browsing ruminants had statistically different numbers of scratches forming discrete data clusters. Perissodactyls differ in the numbers of scratches and pits but without discrete browser and grazer clusters. Microwear features were distributed homogeneously across ruminantmolars and strongly predictive of diet fromthe labial edge of the molar to the lingual edge. Microwear was heterogeneously distributed across perissodactyl molars with more pits on the labial edge andmore scratches on the lingual edge. In perissodactyls, microwear sampled from the labial edge was strongly predictive of diet, while microwear sampled from other areas were not. Discriminant function analyses of microwear assigned individual molars to diets (browser and grazer) and clades (ruminant and perissodactyl) with similar success (70–73%) indicating that phylogeny and diet influencemicrowear equally. Rhino microwear was more sensitive to clade membership while other perissodactyl microwear was more sensitive to diet. Although it is not clear what heritable variables may phylogenetically bias dentalmicrowear, extant ruminants may not be appropriate models for themicrowear of other large herbivores.

The Early Jurassic Toarcian Oceanic Anoxic Event is considered one of the most dramatic environmental perturbations of the Mesozoic. An elevated extinction rate among marine invertebrates accompanied rapid environmental changes, but effects on large vertebrates are less understood. We examined changes in ichthyosaur body size in the Posidonia Shale of the Southwest German Basin spanning the extinction interval to assess how environmental changes and biotic crisis among prey species affected large reptiles. We report no species-level extinction among the ichthyosaurs coinciding with peak invertebrate extinction. Large ichthyosaurs were absent from the fauna during the extinction interval, but became more abundant in the immediate aftermath. Stenopterygius quadriscissus, the most abundant species during the extinction interval, increased in body size after the biotic event. Rapid invasion by large taxa occurred immediately following the extinction event at the end of the first ammonite zone of the early Toarcian. Greater mobility permitting exploitation of ephemeral resources and opportunistic feeding behavior may minimize the impacts of environmental change on large vertebrates.

The small size of Early Triassic marine organisms has important implications for the ecological and environmental pressures operating during and after the end-Permian mass extinction. However, this “Lilliput Effect” has only been documented quantitatively in a few invertebrate clades. Moreover, the discovery of Early Triassic gastropod specimens larger than any previously known has called the extent and duration of the Early Triassic size reduction into question. Here, we document and compare Permian-Triassic body size trends globally in eight marine clades (gastropods, bivalves, calcitic and phosphatic brachiopods, ammonoids, ostracods, conodonts, and foraminiferans). Our database contains maximum size measurements for 11,224 specimens and 2,743 species spanning the Late Permian through the Middle to Late Triassic. The Permian/Triassic boundary (PTB) shows more size reduction among species than any other interval. For most higher taxa, maximum and median size among species decreased dramatically from the latest Permian (Changhsingian) to the earliest Triassic (Induan), and then increased during Olenekian (late Early Triassic) and Anisian (early Middle Triassic) time. During the Induan, the only higher taxon much larger than its long-term mean size was the ammonoids; they increased significantly in median size across the PTB, a response perhaps related to their comparatively rapid diversity recovery after the end-Permian extinction. The loss of large species in multiple clades across the PTB resulted from both selective extinction of larger species and evolution of surviving lineages toward smaller sizes. The within-lineage component of size decrease suggests that only part of the size decrease can be related to the end-Permian kill mechanism; in addition, Early Triassic environmental conditions or ecological pressures must have continued to favor small body size as well. After the end-Permian extinction, size decrease occurred across ecologically and physiologically disparate clades, but this size reduction was limited to the first part of the Early Triassic (Induan). Nektonic habitat or physiological buffering capacity may explain the contrast of Early Triassic size increase and diversification in ammonoids versus size reduction and slow recovery in benthic clades.

Thalattosuchians are crocodylomorphs mainly known from marine strata of Early Jurassic to Early Cretaceous age. They represent the earliest crocodylomorph radiation to an aquatic habitat and their evolutionary history offers very few records from freshwater settings. Here, we report several exquisitely preserved thalattosuchian skulls attributed to a derived teleosaurid from a pedogenic horizon located at the base of a fluvial series of alternating silts and sandstones of the Phu Kradung Formation (Upper Jurassic) of northeastern Thailand. Using laser ablation multicollector inductively coupled mass spectrometry (MC-ICP-MS) on tooth enamel and dentine, we measured isotopic ratios of strontium (⁸⁷Sr/⁸⁶Sr) to test the habitat of these teleosaurids. In addition, Sr concentrations of the dental tissues were estimated from the calibrated signal intensities of the Sr isotope measurements. The dataset includes bioapatite (teeth or scales) of eight terrestrial and five aquatic vertebrates. Theropods exhibit lower Sr concentrations both in enamel and dentine compared to others groups, a pattern in accordance with the calcium biopurification process, which predicts that Sr concentrations in the body of vertebrates decrease up the trophic chain. It also excludes the possibility that diagenesis has completely overprinted the Sr isotope compositions of the fossil assemblage, which exhibits a homogeneous ⁸⁷Sr/⁸⁶Sr signature above the Late Jurassic seawater value. Values for teleosaurid teeth are in the range of other values for vertebrates in the continental assemblage and imply that these crocodylomorphs did not migrate between freshwater and marine habitats at least in the time constraint of the mineralizing tooth. This result represents the first demonstration that a population of teleosaurids was established for a prolonged time in a freshwater environment.Whether the ability of teleosaurids to inhabit freshwater habitats is a secondary adaptation or whether it is plesiomorphic and inherited from freshwater ancestors is discussed.

This study uses a comprehensive, revised, and updated global bivalve dataset combining information from two major databases available to study temporal trends in Phanerozoic bivalve richness: the Sepkoski Compendium and the Paleobiology Database. This compilation results in greater taxonomic and stratigraphic coverage than possible with either of the two databases alone. However, there are challenges in directly comparing these two sources due to differences in their taxonomic designations and stratigraphic range information. Moreover, both of these datasets are fraught with a number of taxonomic errors, which can significantly bias the overall richness estimate. Additionally, a substantial number of taxonomic corrections were made before a new Phanerozoic bivalve richness curve was produced. The new generic taxonomic curve is comparablewith the trajectory of the Sepkoski'smodern fauna and shows rapid and substantial diversification through the Ordovician, followed by a Paleozoic plateau, aMesozoic high, and Cenozoic diversification after a small reduction in richness associated with the K/Pg extinction. The steepCenozoic rise documented in the rawrichness curve derived fromthe new dataset is likely real, and reflects the overall robustness and completeness of the bivalve fossil record.