Eoseira Temporal range: | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Stramenopiles |
Phylum: | Gyrista |
Subphylum: | Ochrophytina |
Class: | Bacillariophyceae |
Order: | Aulacoseirales |
Family: | Aulacoseiraceae |
Genus: | † Eoseira A.P.Wolfe & M.B.Edlund, 2005 |
Species: | †E. wilsonii |
Binomial name | |
†Eoseira wilsonii A.P.Wolfe & M.B.Edlund, 2005 | |
Eoseira is an extinct genus of diatoms belonging to the family Aulacoseiraceae and containing the single species Eoseira wilsonii. The species is dated to the Early Eocenes Ypresian stage and have only been found at the type locality in east central British Columbia.
Eoseira wilsonii was an algal bloom forming diatom during the Early Eocene Climatic Optimum [1] and one of the major lake components the Horsefly Shales lake system. The Horsefly shales have not been radiometrically dated, but based on shared floral and faunal taxa found in the other Early Eocene, Ypresian age, Okanagan Highlands sites, Horsefly is assumed to be contemporaneous. [2]
Diatom fossils at Horsefly had been noted by Mark Wilson and Adrian Bogan (1994) who identified significant diatom volumes in the "summer varves" during study of a 6,375 year long stratigraphic section. [3] Fossil material was studied subsequently by Alexander Wolfe and Mark Edlund (2005) with the type description of the species being published in the Canadian Journal of Earth Sciences . [4] [5] [6] They designated three type specimens at the time of publication, the holotype "CANA 76143" and paratype "BCr; CANA 76144" which were both accessioned into the Canadian Museum of Nature at Ottawa, while the isotype was placed in the California Academy of Sciences Diatom Herbarium. Both the holotype and isotype were collected from the lower (H2) varve sequence exposed at the Horsefly mine locality. The paratype was collected at the nearby outcrops along the Black Creek Road. Wolfe and Edlund coined the specific epithet wilsonii as a patronym honoring Mark Wilson as recognition for his enormous work on western North American Eocene lake paleolimnology and paleoichthyology. They did not give an etymology for the genus name Eoseira. [4]
E. wilsonii was placed into the family Aulacoseiraceae based on the numerous similarities to other members of the family, but placed into the monotypic new genus Eoseira due to a suite of distinctive features. [4] Aulacoseiraceae is considered one of the first diatom families to transition from marine to freshwater habitats, sometime during the Cretaceous. The oldest genus of the family is Aulacoseira, from which Eoseira and other undescribed genera branched from in the Eocene, while a second diversification even took place in the Miocene resulting in the extinct genera Alveolophora , Miosira , and Pseudoaulacosira . E. wilsonii is suggested to be a sister branch to the aulacoseiroid lineages. [4]
Eoseira wilsonii grew valve frustules with a cylindrical cross-section when viewed from the end, and a rectangular outline when viewed from the side. The individual valves formed linked filaments, with many individual frustules connected end to end by an interlinking collar of spines that arise from the face-side junction. The spines on a valve are spoon-shaped with a narrow base widening to an ovoid tip and dovetailing with the spines of the next valve. Each spine is smooth on the external surface and along the inner margins. [4] The sides of the valves are stippled with straight rows of areolae oriented parallel to each other and perpendicular to the valve end faces. Unlike in Aulacoseira enlarged single or paired areolae groups do not form the linking or separation spines, rather the spines arise entirety separate from the areolae. Each of the areolae has a thin, porous silica layer, a vela, on the internal side of the opening. In contrast, as is seen in Aulacoseira, the valves of E. wilsonii develop a distinct ringleiste on the internal surface of the valves. Between the ringleist and valve junction are a number of sessile pore openings through the valve surface, called rimoportulae. The two halves of the valves are linked via girdle bands with connecting ligulate strands which developed parallel poroid rows oriented perpendicular to the valve ends. [4]
The polysaccharide slime grown by E. wilsonii is suggested to have enhanced the preservation quality of organisms which were coated by the slime films before entombment in the lake sediments. [4] The horsefly lake system has been interpreted as monomictic to possibly meromictic. If the lake was monomictic, the lake waters would have one period of surface layer and deep water mixing a year, but if it was meromictic, the water layers did not have any annual periods of mixing. [7] E. wilsonii is one of two diatoms known from Horsefly, with an undescribed species of Aulacoseira also being present. Unlike Aulacoseira giraffensis from the similarly aged Giraffe maar kimberlite pipe deposit in the North West Territories however, the undescribed Horsefly Aulacoseira species was a minor component of the lake flora, with E. wilsonii being the dominatant bloom florming species. [8] Additionally the extant synurid "algae" species Mallomonas intermedia has also been recovered from Horsefly, [7] while study of diatomitic sediments by George Mustoe (2005) from the McAbee Fossil Beds show undescribed Aulacoseiraceae diatoms and chrysophyte stomatocysts. Mustoe also examined sediment from the Allenby Formation near Princeton and found diatomitic layers, but noted that alteration and remineralization of the opal-A to opal-CT destroyed the original organic structures in the diatomite. [9]
The greater Eocene Okanagan Highlands likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable. [10] The Okanagan Highlands paleoforest surrounding the lakes have been described as precursors to the modern temperate broadleaf and mixed forests of Eastern North America and Eastern Asia. Based on the fossil biotas the lakes were higher and cooler then the coeval coastal forests preserved in the Puget Group and Chuckanut Formation of Western Washington, which are described as lowland tropical forest ecosystems. Estimates of the paleoelevation range between 0.7–1.2 km (0.43–0.75 mi) higher than the coastal forests. This is consistent with the paleoelevation estimates for the lake systems, which range between 1.1–2.9 km (1,100–2,900 m), which is similar to the modern elevation 0.8 km (0.50 mi), but higher. [10] Estimates of the mean annual temperature have been derived from leaf margin analysis (LMA) of the Horsefly shales with the LMA returning a mean annual temperature of approximately 10.4 ± 2.2 °C (50.7 ± 4.0 °F). The estimated cold month mean temperature during the winter is placed at approximately 5.3 ± 2.8 °C (41.5 ± 5.0 °F). These estimates are lower than the mean annual temperature estimates given for the coastal Puget Group, which is estimated to have been between 15–18.6 °C (59.0–65.5 °F). The bioclimatic analysis for Horsefly suggests a mean annual precipitation amount of 105 ± 47 cm (41 ± 19 in). [10]
The Okanagan Highlands fossil sites, which includes the Eocene formations between the Driftwood Shales near Smithers, British Columbia in the north and the Klondike Mountain Formation surrounding Republic, Washington to the south have been described collectively as one of the "Great Canadian Lagerstätten " [11] based on the diversity, quality and unique nature of the biotas that are preserved. The highlands temperate biome preserved across such a large transect of lakes recorded many of the earliest appearances of modern genera, while also documenting the last stands of ancient lines. [11] The warm temperate highland floras in association with downfaulted lacustrine basins and active volcanism are noted to have no exact modern equivalents. This is due to the more seasonally equitable conditions of the Early Eocene, resulting in much lower seasonal temperature shifts. However, the highlands have been compared to the upland ecological islands in the Virunga Mountains within the Albertine Rift of the African rift valley. [12]
Tilia johnsoni is an extinct species of flowering plant in the family Malvaceae that, as a member of the genus Tilia, is related to modern lindens. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States and a similar aged formation in British Columbia, Canada.
The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation is comprised of volcanic rocks in the upper unit and volcanic plus lacustrine (lakebed) sedimentation in the lower unit. the formation is named for the type location designated in 1962, Klondike Mountain northeast of Republic, Washington. The formation is a lagerstätte with exceptionally well-preserved plant and insect fossils has been found, along with fossil epithermal hot springs.
The McAbee Fossil Beds is a Heritage Site that protects an Eocene Epoch fossil locality east of Cache Creek, British Columbia, Canada, just north of and visible from Provincial Highway 97 / the Trans-Canada Highway. The McAbee Fossil Beds, comprising 548.23 hectares, were officially designated a Provincial Heritage Site under British Columbia's Heritage Conservation Act on July 19, 2012. The site is part of an old lake bed which was deposited about 52 million years ago and is internationally recognised for the diversity of plant, insect, and fish fossils found there. Similar fossil beds in Eocene lake sediments, also known for their well preserved plant, insect and fish fossils, are found at Driftwood Canyon Provincial Park near Smithers in northern British Columbia, on the Horsefly River near Quesnel in central British Columbia, and at Republic in Washington, United States. The Princeton Chert fossil beds in southern British Columbia are also Eocene, but primarily preserve an aquatic plant community. A 2016 review of the early Eocene fossil sites from the interior of British Columbia discusses the history of paleobotanical research at McAbee, the Princeton Chert, Driftwood Canyon, and related Eocene fossil sites such as at Republic.
Hiodon woodruffi is an extinct species of bony fish in the mooneye family, Hiodontidae. The species is known from fossils found in the early Eocene deposits of northern Washington state in the United States and late Eocene deposits in northwestern Montana. The species was first described as Eohiodon woodruffi. H. woodruffi is one of two Eocene Okanagan Highlands mooneye species, and one of five fish identified in the Klondike Mountain Formation.
Amia? hesperia is an extinct species of bony fish in the bowfin family, Amiidae. The species is known from fossils found in the early Eocene deposits of northern Washington state in the United States and southeastern British Columbia. The species is one of eight fish species identified in the Eocene Okanagan Highlands paleofauna.
Barghoornia is an extinct genus of flowering plants in the family Burseraceae containing the solitary species Barghoornia oblongifolia. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States.
Acer spitzi is an extinct maple species in the family Sapindaceae described from a single fossil samara. The species is solely known from the Early Eocene sediments exposed in northeast Washington state, United States. It is the only species belonging to the extinct section Spitza.
Carpinus perryae is an extinct species of hornbeam known from fossil fruits found in the Klondike Mountain Formation deposits of northern Washington state, dated to the early Eocene Ypresian stage. Based on described features, C. perryae is the oldest definite species in the genus Carpinus.
Klondikia is an extinct hymenopteran genus in the ant family Formicidae with a single described species Klondikia whiteae. The species is solely known from the Early Eocene sediments exposed in northeast Washington state, United States. The genus is currently not placed into any ant subfamily, being treated as incertae sedis.
The paleoflora of the Eocene Okanagan Highlands includes all plant and fungi fossils preserved in the Eocene Okanagan Highlands Lagerstätten. The highlands are a series of Early Eocene geological formations which span an 1,000 km (620 mi) transect of British Columbia, Canada and Washington state, United States and are known for the diverse and detailed plant fossils which represent an upland temperate ecosystem immediately after the Paleocene-Eocene thermal maximum, and before the increased cooling of the middle and late Eocene to Oligocene. The fossiliferous deposits of the region were noted as early as 1873, with small amounts of systematic work happening in the 1880-90s on British Columbian sites, and 1920-30s for Washington sites. A returned focus and more detailed descriptive work on the Okanagan Highlands sites revived in the 1970's. The noted richness of agricultural plant families in Republic and Princeton floras resulted in the term "Eocene orchards" being used for the paleofloras.
Pteronepelys, sometimes known as the winged stranger, is an extinct genus of flowering plant of uncertain affinities, which contains the one species, Pteronepelys wehrii. It is known from isolated fossil seeds found in middle Eocene sediments exposed in north central Oregon and Ypresian-age fossils found in Washington, US.
Fagus langevinii is an extinct species of beech in the family Fagaceae. The species is known from fossil fruits, nuts, pollen, and leaves found in the early Eocene deposits of South central British Columbia, and northern Washington state, United States.
Plecia canadensis is an extinct species of Plecia in the fly family Bibionidae. The species is solely known from Early Eocene sediments exposed in central southern British Columbia. The species is one of twenty bibionid species described from the Eocene Okanagan Highlands paleofauna.
The Eocene Okanagan Highlands or Eocene Okanogan Highlands are a series of Early Eocene geological formations which span a 1,000 km (620 mi) transect of British Columbia, Canada, and Washington state, United States. Known for a highly diverse and detailed plant and animal paleobiota the paleolake beds as a whole are considered one of the great Canadian Lagerstätten. The paleobiota represented are of an upland subtropical to temperate ecosystem series immediately after the Paleocene–Eocene thermal maximum, and before the increased cooling of the middle and late Eocene to Oligocene. The fossiliferous deposits of the region were noted as early as 1873, with small amounts of systematic work happening in the 1870–1920s on British Columbian sites, and 1920–1930s for Washington sites. Focus and more detailed descriptive work on the Okanagan Highland sites started in the late 1960s.
Uhlia is an extinct genus of coryphoid palm containing a single species Uhlia allenbyensis. The species is known from permineralized remains recovered from the Princeton Chert in British Columbia, Canada. Leaves of Uhlia have "tar spot"-like fungal infections of the extinct ascomycete Paleoserenomyces, which in turn are hyperparasitized by the ascomycete Cryptodidymosphaerites.
Paleoserenomyces is an extinct monotypic genus of pleosporale fungus of uncertain family placement. When described it contained the single species Paleoserenomyces allenbyensis. The genus is solely known from the Early Eocene, Ypresian aged, Princeton Chert deposit of the Allenby Formation. Palaeoserenomyces is one of only three described fossil fungus species found in the Princeton Chert, being a tar spot like parasite of the fossil palm Uhlia allenbyensis, and is host for the hyperparasite Cryptodidymosphaerites princetonensis.
Promastax is a genus of "monkey grasshoppers" belonging to the extinct monotypic family Promastacidae and containing the single species Promastax archaicus. The species is dated to the Early Eocenes Ypresian stage and has only been found at the type locality in east central British Columbia.
Alnus parvifolia is an extinct species of flowering plant in the family Betulaceae related to the modern birches. The species is known from fossil leaves and possible fruits found in early Eocene sites of northern Washington state, United States, and central British Columbia, Canada.
Plecia avus is an extinct species of Plecia in the March fly family Bibionidae and is solely known from Early Eocene sediments exposed in central southern British Columbia. The species is one of twenty bibionid species described from the Eocene Okanagan Highlands.
Republicopteron is an extinct orthopteran genus in the katydid-like family Palaeorehniidae with a single described species, Republicopteron douseae.