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As of September 2019, the Florida Museum of Natural History (FLMNH) had a curated collection of 117,449 chondrichthyan specimens from Florida, spanning the Eocene through the Pleistocene. Herein, I evaluate the completeness of the chondrichthyan fossil record from Florida based on the FLMNH collection, while analyzing patterns in taxonomic and ecomorphological diversity. At least 70 chondrichthyan taxa were recognized, representing 10 orders, 26 families, and 42 genera; of which, 20 taxa represent first occurrences from Florida. A sample of 107,698 specimens was organized into 12 time bins to analyze taxonomic and ecomorphological diversity, with an expectation that diversity patterns would correspond with global climate events (e.g., the Eocene–Oligocene transition and the middle Miocene climatic optimum). However, diversity patterns were obscured by pervasive sampling bias, attributable to variable collection methods, research prioritizations, and regional lithologic controls. Sampling is particularly poor for smaller specimens and older geologic units (e.g., the Paleogene). Despite incomplete sampling of the Florida chondrichthyan fossil record, there was an apparent turnover along the Atlantic and Gulf Coastal Plains from a lamniform- to carcharhiniform-dominated chondrichthyan fauna that occurred during the Eocene. This turnover corresponded with the extinction of many lamniform taxa with grasping-dominated dentition types (e.g., Brachycarcharias, Jaekelotodus, and Macrorhizodus). Selachian taxa that survived the late Eocene extinctions were predominantly represented by cutting-dominant dentition types. As cutting aids in the dismemberment of prey, this may reflect a macroevolutionary trend toward active predation and scavenging on larger prey, such as marine mammals, teleost fish, and other sharks.

The diversity of fishes represented in upper Paleocene microfossil localities in the Ravenscrag Formation near Roche Percée, Saskatchewan, is documented. Thirteen kinds of fishes are recognized. Two chondrosteans are present, a sturgeon and a paddlefish, both represented by small, irregularly shaped, ornamented bony plates. Four kinds of basal neopterygians are identified. Two of these, Atractosteus and Cyclurus, are widely distributed in both Paleocene and Upper Cretaceous localities. The remaining two are unnamed taxa designated Holostean A and Holostean B that were known previously from Upper Cretaceous localities but have not been reported from the Paleocene prior to this report. The presence of these taxa in the late Paleocene further supports the conclusion that basal neopterygians were little affected by the K/Pg mass extinction event. Seven teleosts are present in the assemblage. This assemblage of teleosts is similar to assemblages of upper Paleocene fishes from the Paskapoo Formation of Alberta in the presence of osteoglossomorphs, a gonorhynchiform, the esocid Esox, a percopsiform, and at least one other acanthomorph. It differs in the presence of a generically indeterminate protacanthopterygian designated here as morphotype ES-1 and a teleost of uncertain relationships designated morphotype PT-1. Neither of these taxa is present in the Late Cretaceous, suggesting that they first appeared in the area during the early or middle Paleocene. Comparison of the fish assemblages of the late Paleocene and early Eocene suggests that a major faunal transition occurred at the Paleocene/Eocene boundary, and that this involved a decrease in diversity of basal neopterygians.

The Middle-to-Upper Paleolithic transition in Europe covers the last millennia of Neanderthal life together with the appearance and expansion of Modern Human populations. Culturally, it is defined by the Late Middle Paleolithic succession, and by Early Upper Paleolithic complexes like the Châtelperronian (southwestern Europe), the Protoaurignacian, and the Early Aurignacian. Up to now, the southern boundary for the transition has been established as being situated between France and Iberia, in the Cantabrian façade and Pyrenees. According to this, the central and southern territories of Iberia are claimed to have been the refuge of the last Neanderthals for some additional millennia after they were replaced by anatomically Modern Humans on the rest of the continent. In this paper, we present the Middle-to-Upper Paleolithic transition sequence from Cova Foradada (Tarragona), a cave on the Catalan Mediterranean coastline. Archaeological research has documented a stratigraphic sequence containing a succession of very short-term occupations pertaining to the Châtelperronian, Early Aurignacian, and Gravettian. Cova Foradada therefore represents the southernmost Châtelperronian-Early Aurignacian sequence ever documented in Europe, significantly enlarging the territorial distribution of both cultures and providing an important geographical and chronological reference for understanding Neanderthal disappearance and the complete expansion of anatomically Modern Humans.

The family Anthomyiidae (Diptera) has received very little attention in Portugal and as a consequence the state of knowledge of this group of flies in the country is very insufficient. Until now, only 20 species were known for mainland Portugal, but non-systematic sampling carried out over more than 10 years allowed the discovery of 52 new species for the country, 12 of which are also new to the fauna of the Iberian Peninsula, and three additional species new to mainland Portugal (that had already been reported to the archipelagos of the Azores and Madeira). An updated checklist of the species that are currently known in mainland Portugal is also provided.

The fauna described in this paper was collected from a shale quarry (locally known as the ‘Shale Bank’) on the grounds of Mohonk Mountain House in the lower Hudson Valley, New Paltz, New York. Here we describe the crinoids of the Upper Ordovician (approximately 450 million years old) Martinsburg Formation. The Martinsburg consists of a medium dark-gray shale interbedded with sandstone beds that show graded bedding and cross laminae. The fauna includes a new species of Pycnocrinus, as well as the long-stemmed, small-crowned inadunate crinoids Ectenocrinus, Cincinnaticrinus, and Merocrinus, which are also present in several other Late Ordovician offshore faunas. The modes of life of the crinoids are reconstructed, based particularly on stem lengths and aspects of feeding related to the density of branching in the crinoids’ arms. This fossil occurrence probably represents a relatively low energy, offshore mud bottom environment that was episodically stirred by storm waves and currents. A new crinoid fauna has been discovered in the Upper Ordovician (Katian) Martinsburg Formation at a small shale quarry, locally known as the ‘Shale Bank,’ on the Shawangunk Ridge in Ulster County, NY. The assemblage, which is from a relatively low energy, offshore mud-bottom environment, includes four identified species, including a new species of glyptocrinid camerate, Pycnocrinus mohonkensis n. sp., described herein. Crinoid taxa in order of increasing branch density in the assemblage include (1) the dicyclic inadunate Merocrinus curtus with irregularly isotomous and heterotomous, non-pinnulate arms and a stout cylindrical column exceeding 700 mm; (2) the disparids Cincinnaticrinus varibrachialus, with heterotomous non pinnulate arms, and Ectenocrinus simplex, with extensively branched ramulate arms and meric columns of 460–500 mm; and (3) the camerate Pycnocrinus mohonkensis n. sp., with uniserial pinnulate arms and a somewhat shorter column. Some cylindrical stems with nodose and holomeric columnals are thought to belong to unknown camerate crinoids with pinnulate arms. Filtration theory is used to model food capture in the Martinsburg crinoids. Surprisingly, even densely pinnulate camerates were able to survive in this setting, suggesting that ambient currents attained velocities exceeding 25 cm/sec even in this offshore setting. Similar assemblages were widespread in eastern Laurentia during the Late Ordovician.

The fossil record of the Pacific Northwest records millions of years of changing climate and evolving organisms, shedding light not only on life of the past, but also giving us the tools to better predict how future environmental change might play out. A site near Pendleton, Oregon is especially important to understanding ancient ecosystems because it preserves a complete community of vertebrates, from bats and shrews to rhinos and saber-toothed cats. In 2017 and 2021, we returned to this site to collect new fossils. We also visited museum collections that contain fossils from the site to open as clear a window as possible into this 5–6 million year old world. We identified many species new to the site, many of which are also new to the Northwest. These include a bone-crushing dog; camels, both giant and llama-like; an extinct animal that looked like a deer, but that has no modern relatives; and at least two types of ancient horse. We also compiled a complete, up-to-date list of all the mammals ever found at the site. Besides giving us a better idea of what lived in the Pendleton area in the Miocene Epoch, this work will serve as a jumping-off point for later studies focused on how these organisms behaved, functioned, and interacted with each other and with their environments. Encompassing global cooling, the spread of grasslands, and biogeographic interchanges, the Hemphillian North American Land Mammal Age is an important interval for understanding the factors driving ecological and evolutionary change through time. McKay Reservoir near Pendleton, Oregon is a natural laboratory for analyses of these factors. It is remarkable for its small vertebrate fauna including rodents, bats, turtles, and lagomorphs, but also for its larger mammal fossils like camelids, rhinocerotids, canids, and felids. Despite the importance of the site, few revisions to its faunal list have been published since its original description. We expand on this description by identifying taxa not previously known from McKay Reservoir based on specimens collected during fieldwork and through reidentification of previously collected fossils. Newly identified taxa include the borophagine canid Borophagus secundus (Matthew and Cook, 1909), the camelids MegatylopusMatthew and Cook, 1909 and PleiolamaWebb and Meachen, 2004, a dromomerycid, and the equids CormohipparionSkinner and MacFadden, 1977 and PseudhipparionAmeghino, 1904. Specimens previously assigned to NeohipparionGidley, 1903 and Hipparionde Christol, 1832 lack the features necessary to diagnose these genera, which are therefore removed from the site's faunal list. The presence of Borophagus secundus, Cormohipparion, and Pseudhipparion is especially important, because each occurrence represents a major geographic range extension. This refined understanding of the fauna lays the foundation for future studies of taphonomy, taxonomy, functional morphology, and paleoecology—potentially at the population, community, or ecosystem levels—at this paleobiologically significant Miocene locality.

The Cretaceous/Tertiary (K/Pg) mass extinction has long been viewed as a pivotal event in mammalian evolutionary history, in which the extinction of non-avian dinosaurs allowed mammals to rapidly expand from small-bodied, generalized insectivores to a wide array of body sizes and ecological specializations. Many studies have used global- or continental-scale taxonomic databases to analyze this event on coarse temporal scales, but few studies have documented morphological diversity of mammalian paleocommunities on fine spatiotemporal scales in order to examine ecomorphological selectivity and ecospace filling across this critical transition. Focusing on well-sampled and temporally well-constrained mammalian faunas across the K/Pg boundary in northeastern Montana, I quantified dental-shape disparity and morphospace occupancy via landmark- and semilandmark-based geometric morphometrics and mean body size, body-size disparity, and body-size structure via body-mass estimates. My results reveal several key findings: (1) latest Cretaceous mammals, particularly metatherians and multituberculates, had a greater ecomorphological diversity than is generally appreciated, occupying regions of the morphospace that are interpreted as strict carnivory, plant-dominated omnivory, and herbivory; (2) the decline in dental-shape disparity and body-size disparity across the K/Pg boundary shows a pattern of constructive extinction selectivity against larger-bodied dietary specialists, particularly strict carnivores and taxa with plant-based diets, that suggests the kill mechanism was related to depressed primary productivity rather than a globally instantaneous event; (3) the ecomorphological recovery in the earliest Paleocene was fueled by immigrants, namely three multituberculate families (taeniolabidids, microcosmodontids, eucosmodontids) and to a lesser extent archaic ungulates; and (4) despite immediate increases in the taxonomic richness of eutherians, their much-celebrated post-K/Pg ecomorphological expansion had a slower start than is generally perceived and most likely only began 400,000 to 1 million years after the extinction event.

A diverse and well-preserved radiolarian assemblage from the Malongulli Formation, New South Wales, Australia, contains 13 species representing 10 genera and six families. One new genus, Wiradjuri, is introduced to accommodate pre-Devonian single-shelled entactiniid taxa, and one new species, Secuicollacta malongulliensis, is recorded together with some previously described forms. The microstructures of the “rotasphaerid structure/primary unit” and the “ectopic spicule” are investigated to validate their roles as fundamental units in the Secuicollactidae, together with comprehensive documentation of the previously enigmatic Pseudorotasphaera internal skeleton. The results of this investigation suggest that, among all radiolarian genera that survived the Late Ordovician Mass Extinction event (LOME) and transitioned into the Silurian, Secuicollacta, Haplotaeniatum, and Palaeoephippium maintained stable body plans during the transition and were more successfully established. The selective advantages these lineages had during the LOME were most likely spontaneous outcomes of the mode of structural development involving sequential skeletogenesis and a tendency to evolve toward simpler body plans.

The ca. 780–740 Ma Chuar Group, Grand Canyon, Arizona, provides an exceptional record of life during the diversification of crown-group eukaryotes, just prior to the first Cryogenian glaciation. We document in detail the assemblage of organic-walled microfossils preserved in fine-grained siliciclastics throughout the unit. In contrast with earlier studies, we primarily used SEM to document fossil morphologies, augmented by transmitted light microscopy, FIB-SEM, and TEM. This resulted in the discovery of new species and the recognition of broad-ranging, intraspecific biological and taphonomic variation in other species. Twenty-two species and five unnamed morphotypes are described, including three new species: Kaibabia gemmulella, Microlepidopalla mira, and Volleyballia dehlerae; two new combinations: Galerosphaera walcottii and Lanulatisphaera laufeldii; and 17 previously described forms. The possible colonial green alga Palaeastrum dyptocranumButterfield in Butterfield, Knoll, and Swett, 1994 and the index fossil Cerebrosphaera globosa (Ogurtsova and Sergeev, 1989) Sergeev and Schopf, 2010 (= C. buickii Butter-field, 1994) are described for the first time from Chuar rocks. Lanulatisphaera laufeldii, a locally abundant and globally widespread species characterized by submicrometer filamentous processes that form a reticulate network, may be a useful marker for the time interval just before the appearance of vase-shaped microfossils (VSMs) ca. 740 Ma. Organic-walled microfossil assemblages decline in diversity upsection, coincident with the appearance of VSMs and intermittent euxinia within the basin. Whether this pattern is due to preservational bias related to greater water depth or the higher TOC of upper Chuar rocks or instead reflects biotic turnover related to the spread of euxinic water masses in the basin is unknown.

Reduction of body size is a common response of organisms to environmental stress. Studying the early Toarcian succession in the Lusitanian Basin of Portugal, we tested whether the shell size of benthic marine communities of bivalves and brachiopods changed at and before the global, warming–related Toarcian oceanic anoxic event (T-OAE). Statistical analyses of shell size over time show that the mean shell size of communities decreased significantly before the T-OAE. This trend is distinct in brachiopods and is caused by larger-sized species becoming less abundant over time, whereas it is not significant in bivalves, suggesting a decoupled response to environmental stress. Reductions in shell size precede the decline in standardized sample-level species richness associated with the early Toarcian extinction event. Such decreases in the shell size of marine invertebrates, well before the onset of biodiversity change, suggest that reductions in body size more generally may be a precursor of a subsequent loss of species and turnover at the community level caused by climate change. Sedimentological evidence is against hypoxia as a driver of extinction and the preceding size decrease in the brachiopod fauna in the studied succession, although low oxygen levels are widely held responsible for elevated early Toarcian extinction rates globally. Reduction of mean shell size in brachiopods but stasis in bivalves is difficult to explain with ocean acidification, because experimental work shows that brachiopods can be resilient to lowered pH, albeit long-term metabolic costs and potential evolutionary adaptations are unknown. Rising early Toarcian temperatures in the Lusitanian Basin seem to be a plausible factor in both diversity decline associated with the T-OAE and the preceding reductions in mean shell size, because thermal tolerances in modern bivalves are among the highest within marine invertebrates.