The Upper Triassic of the Williston Lake area of northeastern British Columbia is represented by a nearly continuous series of fossil-rich sediments that were deposited in the Western Canadian Sedimentary Basin in an offshore mid-paleolatitude setting on the western margin of cratonic Pangea. The fossils in this report come primarily from the upper Carnian–upper Norian Pardonet Formation, which has been the subject of numerous paleontologic studies on ammonoids and conodonts, yet has received little attention with regard to its bivalve fauna. Fossil bivalves belonging to the thin-shelled bivalve genera Halobia, Eomonotis, and Monotis dominate the benthic macrofauna and occur within unique shell accumulations that are interpreted to represent oxygen-controlled monospecific paleocommumities that have undergone little post-mortem transportation. Systematic analyses of more than 1,000 individual bivalve specimens resulted in the identification of 25 species-rank taxa, a majority of which belong to the pterioid genus Halobia and the pectinoid genera Eomonotis and Monotis. Of these, four new species are recognized, including 1) upper Carnian Halobia tozeri n. sp. characterized by a unique triangular outline; 2) lowermost Norian Halobia selwyni n. sp. closely related to H. beyrichi and first appearing with H. austriaca which is proposed as a potential datum for the Carnian–Norian boundary; 3) Norian Meleagrinella mclearni n. sp., a new name for previously identified species; and 4) upper Norian Otaparia norica n. sp. which has a delicate thin shell, unique outline, and fine ornament. A revised and refined biochronology of Upper Triassic Bivalvia (chiefly Halobiidae and Monotidae) integrated with conodont and ammonoid zones and standard Triassic stages is presented for the Upper Triassic of the Williston Lake area and permits enhanced correlation to coeval faunas elsewhere in the North American Cordillera, and to the Boreal, Panthalassan and Tethyan faunal realms.

Brontotheriids are common in Eocene faunas of North America and Asia but are poorly known from the Indian subcontinent. Here we describe three new late early Eocene brontotheriids from Pakistan, found in the upper part of the upper Ghazij Formation and representing the oldest Asian brontotheres. Eotitanops pakistanensis n. sp. is a small, primitive species, Balochititanops haqi n. gen. n. sp. is slightly larger and more derived, and fragmentary specimens identified as cf. Balochititanops sp. appear to represent a third, larger taxon.

Improved knowledge of early brontotheres from North America permits better taxonomic resolution of some middle Eocene brontothere remains from Pakistan. ‘Eotitanops’ dayi from the Kuldana Formation is shown to be closer to Palaeosyops and is renamed Palaeosyops dayi n. comb. A new astragalus from the Baska Formation probably represents Pakotitanops latidentatus. A previously described humerus and a new calcaneum, both from the Subathu Formation, are tentatively referred to Mulkrajanops moghliensis.

Phylogenetic interpretation suggests that Eotitanops pakistanensis is as primitive as the North American species of this basal brontothere genus, and also, within the limits of stratigraphic resolution, Eotitanops appeared on both continents at the same time. The origin of brontotheres is therefore equally likely to have been in Asia or in North America. The presence of the primitive brontotheres Eotitanops and Palaeosyops in Indo-Pakistan and North America indicates faunal exchange, almost certainly through Asia, although the direction of dispersal cannot be determined. The postulated high-latitude exchange coincides with a warm interval known as the Early Eocene Climatic Optimum.

The Chesley Drive Group, an Upper Cambrian–Lower Ordovician mudstone-dominated unit, is part of the Ediacaran–Ordovician cover sequence on the North American part of the Avalon microcontinent. The upper Chesley Drive Group on McLeod Brook, Cape Breton Island (previously “McLeod Brook Formation”), has two lithofacies-specific Tremadocian biotas. An older low-diversity benthic assemblage (shallow burrowers, Bathysiphon, phosphatic brachiopods, asaphid trilobites) is in lower upper Tremadocian green-gray mudstone. This wave-influenced, slightly dysoxic facies has Bathysiphon–brachiopod shell lags in ripple troughs. The upper fauna (ca. 483 /− 1 Ma) is in dysoxic-anoxic (d-a), unburrowed, dark gray-black, upper upper (but not uppermost) Tremadocian mudstone with a “mass kill” of the olenid Peltocare rotundifrons (Matthew)—a provincial trilobite in Avalonian North America that likely tolerated low oxygen bottom waters. Scandodus avalonensis Landing n. sp. and Lagenochitina aff. conifundus (Poumot), probable nektic elements and the first upper Tremadocian conodont and chitinozoan reported from Avalon, occur in diagenetic calcareous nodules in the dark gray–black mudstone. An upper Tremadocian transition from lower greenish to upper black mudstone is not exposed on McLeod Brook, but is comparable to a coeval green-black mudstone transition in Avalonian England. The successions suggest that late late Tremadocian (probable Baltic Hunnebergian Age) sea level was higher in Avalon than is suggested from successions on other paleocontinents. The Tremadocian sea-level history of Avalon was a shoaling–deepening–shoaling sequence from d-a black mudstone (lower Tremadocian), to dysoxic green mudstone (lower upper Tremadocian), and back to black mudstone (upper upper Tremadocian).

Scandodus Lindström is emended, with the early species S. avalonensis Landing n. sp. assigned to the emended Family Protopanderodontidae. Triangulodus Van Wamel is considered a junior synonym of Scandodus. Peltocare rotundifrons is emended on the basis of complete specimens.

A dorsal valve of an Upper Cambrian lingulate brachiopod exhibits a repair scar on the anterior lateral edge of its larval shell. This species is characterized by an abrupt change in ornamentation from larval to postlarval growth. Shell material secreted in the injured area after the damage occurred exhibits ornamentation that is characteristic of postlarval growth, although equivalent growth exhibits characteristics of the larval stage. A break in the edge of the shell is visible, and the growth lines of the larval and postlarval shell were distorted until the broken area was filled in. Damage to the surface of the shell is interpreted to have been caused by the same event. Modern lingulate brachiopod larvae are planktotrophic and are interpreted to have been so throughout their long geologic history. Therefore, an environmental cause of shell damage seems unlikely and the injuries are interpreted to have been caused by an unknown durophagous predator. This specimen offers evidence that lingulate brachiopod larvae were able to survive shell breakage and repair their shells.

The family Remingtonocetidae is a basal family of Eocene cetaceans only known from near shore marine environments of India and Pakistan. We describe a new skull for Remingtonocetus harudiensis which elucidates the anatomy and functional morphology of the head and provides new details on cranial cavity and nasopharyngeal region. We suggest that Remingtonocetus was an ambush predator that hunted from a perch on the ocean floor, and that hearing was its most important sense. We speculate that the greatly elongated rostrum is an adaptation for water retention because these are some of the earliest whales living in seawater.

The Cretaceous Huitrín Formation in west-central Argentina records the final connection of the Neuquén Basin to the Pacific Ocean. This formation is comprised of a variety of continental to marginal-marine sediments deposited behind an Andean volcanic arc under warm, arid paleoclimatic conditions. Here we focus on a bivalve fauna from carbonate ramp deposits within the Barremian La Tosca Member of the Huitrín Formation. This fauna is very abundant and widely distributed within the basin but, surprisingly, it has not yet been studied in detail. In addition, paleoenvironmental affinities remain unresolved, with the fauna variously interpreted as having freshwater, brackish, and marine affinities. We studied the fauna's taxonomy and paleoecology based on more than 500 specimens collected at ten fossil localities in combination with new field observations. The bivalve assemblage was recorded from middle to outer carbonate ramp deposits and is composed of five taxa of marine affinity: Phelopteria huitriniana n. sp., Isognomon cf. I. nanus (Behrendsen), Placunopsis? pichi n. sp., Anthonya jarai n. sp., and Argenticyprina mulensis n. gen. n. sp.; the first three may be regarded as eurytopic and/or opportunistic. Reduced diversity, low evenness, overall small size (length <4 cm), thin shells, eurytopic or opportunistic life strategies, and high endemism point to a restricted marine setting for the La Tosca Member. The most important limiting factors likely were low primary productivity and fluctuating salinity and temperature, as conditions inferred for the unit include high evaporation rates combined with low continental runoff and reduced rainfall. Thick evaporite deposits below and above La Tosca Member and thin intercalated gypsum beds support a restricted, hypersaline setting.

The early astogeny of specimens representing the bryozoan genera Dekayia, Parvohallopora, Heterotrypa, and Homotrypella follows the same pattern documented in other Ordovician trepostomes. After larval settlement and metamorphosis, typically three primary, periancestrular, autozooids bud distally from the founder zooid, the ancestrula, with secondary zooids budding from the primaries, tertiary zooids from the secondaries, and so on. Progressive lateral displacement of buds, through backbudding, eventually produces a sub-circular ancestrular disk. Significant intergeneric differences in this basic pattern do not appear to exist. Intrageneric variability in budding pattern occurs during colony development. That variability might have resulted from any or all of the following sources: within-genus plasticity, the development of multiple ancestrulae, or environmental variation. The basic pattern of three primary buds developed from individual ancestrulae has been recognized in other trepostomes, some cyclostomes, and two suborders of cryptostomes. Cladistically, the trait must be considered polyphyletic until more is known about the number of primary buds in the remaining bryozoan suborders. Ancestrular dimensions are statistically similar across genera except between the smaller Dekayia and larger Parvohallopora, but ancestrular sizes in all four Dillsboro genera are consistent with the inference that they possessed a polyembryonic lecithotrophic larval type.

Tentaculitoid microconchid tubeworms from Devonian (uppermost Emsian–upper Givetian) deposits of the Holy Cross Mountains, Poland, include three new species from stratigraphically well-constrained lithological units: Polonoconchus skalensis n. gen. n. sp., Palaeoconchus sanctacrucensis n. sp. and Microconchus vinni n. sp. The microconchids inhabited fully marine environments during transgressive pulses, as is evidenced from facies and associated fossils. Polonoconchus skalensis n. gen. n. sp. and Palaeoconchus sanctacrucensis n. sp. inhabited secondary firm- to hard-substrates in deeper-water, soft-bottom environments. They developed planispiral, completely substrate-cemented tubes and planispiral tubes with elevated apertures, which is indicative of environments where sedimentation rate is low but competition for space (by overgrowth) may be high. Microconchus vinni n. sp., on the other hand, developed a helically coiled distal portion of the tube as a response to a high sedimentation rate. As the taxonomic composition of Devonian microconchids is poorly recognized at both regional and global scales, this new material contributes significantly to our understanding of the diversity of these extinct tube-dwelling encrusters.

The phosphatocopids Hesslandona necopina Müller, 1964 and Hesslandona longispinosa (Kozur, 1974) new combination, recovered from the Upper Cambrian in western Hunan, South China, are described. The ontogenetic stages of H. necopina are revised, with newly defined second and third ontogenetic stages. The second stage is characterized by a bipartite mandibular limb stem consisting of separate coxa and basipod. The third stage is characterized by the partial fusion of the mandibular coxa and basipod. These two parts may become completely fused possibly in a later ontogenetic stage. Vestrogothia longispinosa Kozur, 1974 is reassigned to Hesslandona because of the presence of an interdorsum and a relatively narrow doublure. The new data reported here, plus earlier reports of phosphatocopids from the same section and horizon in western Hunan since 2005, are included in an updated phylogenetic analysis of the Phosphatocopida. Autapomorphies that define several monophyletic groups (e.g., the Crustacea sensu lato, Labrophora, Eucrustacea, Phosphatocopida, Euphosphatocopida, Vestrogothiina, Hesslandonina, and Dorsospinata) are discussed. The present analysis confirms results from earlier phylogenetic analyses in showing the Phosphatocopida-Eucrustacea sister-taxon relationship, but differs from them in supporting the paraphyly of the Hesslandonidae and the monophyly of the Vestrogothiidae.

The skull of the enigmatic turtle Compsemys victa Leidy, 1856 is described. A number of unique characteristics are apparent, including the extremely thick nature of all cranial bones, the presence of rod-like epipterygoids, placement of the foramen posterius canalis carotici interni halfway along the contact between the pterygoid and basisphenoid, lack of cheek emarginations, and the reduction of the size of the cavum tympani relative to the orbit. Two differing global turtle analyses and one paracryptodiran analysis were performed to determine the phylogenetic placement of C. victa. Both global analyses converged by placing C. victa within Paracryptodira, herein defined as the most inclusive clade that includes Pleurosternon bullockii and Baena arenosa, but no species of living turtle, whereas the paracryptodiran analysis places C. victa outside of Baenoidea, herein defined as the least inclusive clade that contains P. bullockii and B. arenosa. Although a number of similarities are apparent between C. victa and the uncommon, extant testudinoid Platysternon megacephalum, the available data indicate that these similarities are convergent, likely due to their carnivorous diet. Taphonomic evidence reveals that basal paracryptodires, including C. victa, preferred slow moving or ponded water environments. The riverine habitat preference of baenodds must therefore be derived.