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Aulacoseira is a freshwater diatom genus found today in numerous lakes, ponds and rivers worldwide, and inhabiting a wide range of environmental conditions. The genus is one of the oldest diatom lineages known to colonize freshwater environments, dating to the late Cretaceous and radiating over much of the Cenozoic. The purpose of this paper is to describe a new species, Aulacoseira chockii, from an early Eocene locality situated near the Arctic Circle in northern Canada. The exquisitely preserved specimens have allowed for a detailed examination of frustule morphology of this early Cenozoic taxon. Three characteristics clearly separate A. chockii from all other known fossil and modern species in the genus. First, the spines of A. chockii are formed by coalescence of extensions from three to five mantle costae and multiple ribs that originate on the valve face. This type of spine design has never been reported and represents a potentially ancient trait in the Aulacoseiraceae lineage. Second, the valve has multiple sessile rimoportulae that are each connected to the end of a tube or canal that runs parallel to, and inside, the mantle wall. Rimoportulae with this structure are rare, and found primarily on extinct species of Aulacoseira. Third, the mantle striae are sinistrorse, and represent another rarely observed character within the genus. Because frustules of A. chockii possessed only separation spines, existed largely as single cells and not in long filaments, and were found in associated with remains of numerous heliozoans as well as testate euglyphids and sponges, it is believed this species grew in the littoral zone of a shallow waterbody. [ABSTRACT FROM AUTHOR]

New specimens of fossil homolid crabs collected from Cretaceous and Paleogene rocks from Canada and the western United States increase the fossil record of the Homolidae De Haan, 1839. Cretalamoha n. gen., n. sp. is reported from the Campanian Pender Formation, Vancouver Island, British Columbia, Canada. A new species, Paromola roseburgensis n. sp. from the early Eocene Roseburg Formation in Oregon, U.S.A. represents the second report for the genus in the fossil record and the first one in North America, extending the spatial and temporal ranges of the genus, from the Oligocene of Argentina to the Eocene of the North Eastern Pacific. Additional material from the Oligocene of Judkins Ridge, near Eugene, Oregon, U.S.A. assigned to Palehomola gorrelli Rathbun, 1926, allows re-evaluation of the systematic position of the genus, previously ascribed to the Homolodromiidae Alcock, 1900. The definite presence of linea homolica justifies removal of Palehomola from this family and inclusion within the Homolidae. [ABSTRACT FROM AUTHOR]

Rotosphaerids are unicellular, heterotrophic, eukayotic protists that have filopodia, an exterior covering consisting of highly ornamented siliceous scales, and are classified in the Rotosphaerida within the opistokont lineage. Given their appearance as relatively large spherical cells with protruding filopodia and a silica scale covering, they are often mistaken for centrohelid heliozoans. Even though these organisms are widely distributed in both marine and freshwater environments, many species are rarely reported, and none have been reported from the fossil record. We report extensive remains of a new species of Rabdiophrys , R. giraffensis , from an ancient waterbody that was situated near the Arctic Circle in northern Canada during the Eocene. The new species has both plate and spine scales that are similar in morphology, but significantly larger than its closest modern congeners, R. monopora and R. anulifera. The waterbody in which the new species grew and thrived is inferred to have been a moderately deep, circumneutral pond, with moderate concentrations of nutrients and dissolved humic material. [ABSTRACT FROM AUTHOR]

Well-preserved siliceous plates representing multiple species of euglyphids are described from a Middle Eocene maar lake deposit located near the Arctic Circle in northern Canada. Siliceous plate morphotypes including scutiform, rectangular, hexagonal, oval and circular body forms, six apertural plate types containing from five to thirteen teeth and spine plates, are documented. Many plate types bear resemblance to those found on modern species as well as ones documented from Miocene sites. These findings extend the known geological record for euglyphids and support the concept of evolutionary stasis in regards to plate morphology over much of the Cenozoic. Future use of these euglyphid remains, in conjunction with other microfossil assemblages, for reconstructing historical conditions within the maar lake is discussed. [ABSTRACT FROM AUTHOR]

The Eocene Princeton Chert locality of southern British Columbia, Canada, provides data to develop organismal concepts for several species of fossil plants, including the first extinct species of Pinaceae, Pinus arnoldii Miller . This new species concept is based on a combination of interconnected organs, common histological features, and patterns of association among isolated plant parts. These data expand our knowledge of P. arnoldii from a morphospecies of ovulate cones to an extinct species of pine that produces woody stems with five-needled fascicles of leaves; simple pollen cones with two abaxial pollen sacs per microsporophyll, containing bisaccate pollen grains; seed cones with inflated scale apices, dorsal umbos that do not bear mucros, and a thick-walled sclerotic outer cortex; and coralloid roots with ectomycorrhizal associations. Organs preserved at various stages of development provide evidence for numerous aspects of growth and reproductive biology, including pollination biology and seed cone development. Cladistic analyses of morphological and molecular characters demonstrate that the novel combination of characters displayed by P. arnoldii causes this extinct species to fall near the base of the Pinus L. tree, either as the sister to all living species of the subgenus Pinus or outside the subgenera that have been defined by extant species of Pinus. [ABSTRACT FROM AUTHOR]

Abstract: Estimates of pCO2 for the early Paleogene vary widely, from near modern-day levels to an order of magnitude greater, based on various proxy measures. Resolving the relationship between climate and pCO2 during this globally warm period is a key task in understanding climate dynamics in a warmer world. Here, we use the stomatal frequency of fossil Ginkgo adiantoides from the Okanagan Highlands of British Columbia, Canada to estimate pCO2 during the Early Eocene Climatic Optimum (EECO), the interval of peak warmth in the Cenozoic. We also examine a dataset of modern Ginkgo biloba leaves to critically assess the accuracy and precision of stomatal frequency as a proxy indicator of pCO2. Early Eocene fossil G. adiantoides has significantly lower stomatal frequency than modern G. biloba, suggesting pCO2 levels >2× modern pre-industrial values. This result is in contrast to earlier studies using stomatal frequency of Ginkgo that indicated near modern-day levels of pCO2 in the early Paleogene, though not including samples from the EECO. We also find that levels of pCO2 as indicated by stomatal frequency are correlated with trends in climate (mean annual temperature) over time at the Falkland fossil locality, suggesting that climate and pCO2 were coupled during the EECO hyperthermal. [Copyright &y& Elsevier]

The evolutionary history of diatoms is only constrained partially by the fossil record. The timing of several key events, such as initial colonization of freshwater habitats by marine taxa, remains poorly resolved. Numerous specimens of the genera Cyclotella, Discostella, and Puncticulata (Ochrophyta: Thalassiosirales) have been recovered in Middle Eocene lacustrine sediments from the Giraffe Pipe locality in the Northwest Territories, Canada. These diatoms extend the fossil record of the family Stephanodiscaceae to at least 40 million years before present (Ma) and thus provide a new evolutionary milepost for the thalassiosiroid diatoms, an important dade of centric diatoms with global representation in both marine and freshwater environments. The quality of the fossil material enables detailed investigations of areolae, fultoportulae, and rimoportulae, revealing direct morphological affinities with a number of extant taxa. These observations extend the antiquity of several characters of phylogenetic importance within the thalassiosiroid diatoms, including the fultoportula, and imply that the entire lineage is considerably older than prior constraints from the fossil record, as suggested independently by several recent molecular phylogenies. [ABSTRACT FROM AUTHOR]

Several fertile pinnules with abaxially borne sporangia have been discovered in calcareous marine nodules from the Middle or Late Eocene Appian Way locality on the east coast of Vancouver Island, British Columbia, Canada. Fertile pinnules are attached in groups of two or three. They are deeply lobed, with each lobe rolled toward the abaxial surface and the entire pinnule rolled toward the abaxial surface to form an irregularly globose structure. Sporangia occur abaxially and form two rows over the entire surface of each pinnule lobe. The midrib of each pinnule lobe is thickened, forming a receptacle from which broadly attached sporangia and numerous paraphyses diverge. As is characteristic of many schizaeaceous ferns, sporangia of the fossil are flask shaped with a short stalk and have a uniseriate, transverse annulus at the apex. Spores are tetrahedral and trilete, like those of the type species for the extinct genus Paralygodium. The new specimens are described as Paralygodium vancouverensis sp. nov. and are compared to both living genera of schizaeaceous ferns and the extinct species Paralygodium yezoense and Anemia poolensis. The unique combination of characters displayed by each of the fossil species reveals the presence of several extinct schizaeaceous lineages and supports interpretations that the diversity of Schizaeaceae s.l. was greater during the Cretaceous and Paleogene than it is today. [ABSTRACT FROM AUTHOR]

This is the first documentation of scaled chrysophytes of Tertiary age. Siliceous scales belonging to four genera (Synura, Mallomonas, Chrysosphaerella, and Spiniferomonas) are preserved in middle Eocene (∼47 Ma) lacustrine mudstones deposited in a posteruptive crater associated with kimberlite intrusion near Lac de Gras, Northwest Territories, Canada. Astonishingly, most of these microfossils have remarkable morphological affinities with extant congeneric taxa, indicating that the unique siliceous ornamentation of the scaled chrysophytes, including scales, spines, and bristles, was fully evolved by the middle Eocene. These observations imply that the scaled chrysophytes experienced prolonged intervals of relative evolutionary stasis during Neogene and Quaternary times and thus provide a new evolutionary milepost for this algal group. [ABSTRACT FROM AUTHOR]

A permineralized lythraceous leaf type found in close association with fruits, stems, and roots of Decodon allenbyensis Cevallos Ferriz et Stockey in the Middle Eocene Princeton chert of British Columbia, Canada, is described. Midribs have a prominent C-shaped midvein surrounded by sclerenchyma, with an adaxial epidermis of rectangular to rounded cells lacking enlarged mucilage cells. Leaves are dorsiventral, 180-270 µm thick at the lamina, with a double palisade layer. Abaxial epidermal cells have prominent papillae, and these epidermal cells can be infected by fungi, forming dark sterile stromata. Fossil leaves are similar to those of Myrtales and are compared to those of Lythraceae sensu lato. Although these leaves are thought to belong to the previously described Decodon allenbyensis found in the same chert layer, they lack the diagnostic features of extant Decodon leaves. Instead they share most anatomical similarities with Duabanga grandiflora Roxburgh ex DC Walpers (Lythraceae, subfamily Duabangoideae) including vascular tissues, palisade and spongy mesophyll, bundle fibers, and abaxial epidermal papillae. Duabanga grandiflora differs from the fossil in having mucilaginous cells and a consistently V-shaped abaxial midrib. Although anatomically similar to Duabanga, the fossil leaves are considered those of D. allenbyensis, based on association and the depositional environment prior to preservation. Recent phylogenetic analyses place Duabanga and Decodon in separate clades within Lythraceae, but relationships between these clades are not well supported, indicating that fossil leaves should provide useful anatomical characters for elucidating relationships within Lythraceae. [ABSTRACT FROM AUTHOR]

The ultrastructural examination by transmission electron microscopy of 45-million-year-old mummified leaves of Metasequoia extracted from the Upper Coal member of the Buchanan Lake Formation in Napartulik on Axel Heiberg Island revealed the preservation of intact chloroplasts and chloroplast components. Abundant tanniferous cell inclusions may indicate that the 3-mo period of constant daylight during the Artic summer induced high concentrations of tannins in the leaf tissues, which may have arrested microbial degradation of the litter. Quantified differences in the extent of chloroplast preservation through a vertical section of the lignite suggest that short-term shifts in the depositional environment took place, perhaps influencing the exposure of the leaf tissues to conditions that would either promote or inhibit decomposition. [ABSTRACT FROM AUTHOR]

Two fossil poroid hymenophore fragments, one from the Cretaceous Period and the other from the Eocene Epoch, are described. The permineralized specimens were obtained from marine calcareous concretions on Vancouver Island, British Columbia, Canada, and were studied using the cellulose acetate peel technique. Size and distribution of pores in the hymenophores, as well as the hyphal anatomy of the dissepiments arid some hymenial elements, were examined. In the Cretaceous specimen, Quatsinoporites cranhamii sp. nov., pores are round to elliptical, three per mm, and 130-540 µm diam. Dissepiments consist of narrow, simple septate, hyphae. Neither basidia nor basidiospores are present, but acuminate hymenial cystidia, up to 54 µm in length, are common. The Eocene specimen, Appianoporites vancouverensis sp. nov., has a pore density of six per mm and pores are 130-163 µm in diam. Dissepiments consist of narrow, simple septate, thin-walled hyphae. Neither basidia nor basidiospores are present, but acuminate, thick-walled hymenial cystidia, up to 32 µm in length, are common. The poroid hymenophore is a characteristic of a number of extant basidiomycete taxa, including the Boletales, Polyporales and Hymenochaetales. It is unlikely that the fleshy, ephemeral, terrestrial basidiomata of the Boletales would be preserved in a marine environment, and thus the specimens are interpreted as belonging to basidiomycete lineages, with persistent, leathery or corky basidiomata. The simple septate hyphae, the minute pores and presence of cystidia most closely resemble taxa of the Hymenochaetales. These fossils unequivocally push back the minimum age of homobasidiomycetes and extend their paleogeographical range. [ABSTRACT FROM AUTHOR]

Potassic silica-undersaturated mafic volcanic rocks form a minor portion of the predominantly calc–alkaline Eocene Challis–Kamloops volcanic belt, which extends from the northwestern United States into central British Columbia (Canada). Their major occurrence is in the Penticton Group in south central British Columbia, where they reach a thickness of up to 500 m and form the northwestern edge of the Montana alkaline province. These analcime-bearing rocks (∼53–52 Ma old) are typically rhomb porphyries of ternary feldspar (An28Ab52Or20). Additional phenocryst phases include clinopyroxene, analcime, phlogopite and rare olivine. The rocks are characterized by high total alkalis, particularly K2O (>4.5 wt%) as well as by a distinct enrichment of large-ion lithophile elements versus heavy rare-earth elements and high-field-strength elements. They have unusual isotopic compositions compared to most other rocks of the Challis–Kamloops belt, particularly high negative ∊Nd values and elevated but relatively uniform initial 87Sr/86Sr ratios (∼0.7065). The potassic silica-undersaturated rocks overlie Precambrian crust and lithosphere and were at least in part derived from ancient metasomatized subcontinental mantle lithosphere, which was modified in a Precambrian subduction setting. The alkaline rocks of the Challis–Kamloops belt are related to a slab-window environment. In particular, they were formed above the southern edge of the Kula plate adjacent to the Kula–Farallon slab window, whereas the Montana alkaline province situated well to the southeast was formed directly above the Kula–Farallon slab window. Upwelling of the hotter asthenospheric mantle may have been the thermal trigger necessary to induce melting of fertile and metasomatized lithospheric mantle. [Copyright &y& Elsevier]

Middle Eocene lacustrine deposits in south-central British Columbia and north-central Washington state preserve two types of Ginkgo leaves. A morphotype characterized by deeply divided multiple lobes is herein described as Ginkgo dissecta sp.nov. Leaves that are either undivided or shallowly divided into bilobate symmetry are indistinguishable from foliage of extant Ginkgo biloba Linnaeus. These fossils contradict the widely held belief that only a single Ginkgo species, Ginkgo adiantoides (Unger) Heer, inhabited Cenozoic forests.Key words: British Columbia, Eocene, fossil, Ginkgo adiantoides, Ginkgo biloba, Ginkgo dissecta, McAbee, Republic, Tertiary, Washington.Des dépôts lacustres de l'Éocène moyen, dans le centre-sud de la Colombie-Britannique et le centre-nord de l'état de Washington, ont permis la conservation de deux types de feuilles du Ginkgo. On décrit ici le Ginkgo dissecta sp.nov., un morphotype caractérisé par des lobes multiples profondément divisés. Les feuilles qui sont soit indivises ou faiblement divisées selon une symétrie bilobée sont indistinctes du feuillage du Ginkgo biloba Linnaeus actuel. Ces fossiles contredisent l'idée reçue qu'une seule espèce de Ginkgo, le Ginkgo adiantoides (Unger) Heer, habitait les forêts mésozoïques.Mots clés : Colombie-Britannique, Eocène, fossile, Ginkgo adiantoides, Ginkgo biloba, Ginkgo dissecta, McAbee, Republic, tertiaire, Washington.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]