WThe Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation, named for the type location designated in 1962, Klondike Mountain north of Republic, Washington, is composed of volcanic rocks in the upper unit and volcanics plus lacustrine (lakebed) sedimentation in which a lagerstätte with exceptionally well-preserved plant and insect fossils has been found, along with fossil epithermal hot springs.
WAbies milleri, an extinct species of fir known from fossil remains found in deposits from the early Eocene Ypresian stage in Washington State, USA, is the oldest confirmed record for the fir genus.
WAinigmapsychops is an extinct genus of lacewing in the silky lacewing family Psychopsidae. The genus is solely known from an Eocene fossil found in North America. At the time of its description the new genus was composed of a single species, Ainigmapsychops inexspectatus.
WAllorapisma is an extinct genus of lacewing in the moth lacewings family Ithonidae. The genus is solely known from two Eocene fossils found in North America. At the time of description the genus was composed of a single species, Allorapisma chuorum.
WAzolla is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like other typical ferns but more resembling duckweed or some mosses. Azolla filiculoides is one of just two fern species for which a reference genome has been published.
WBarghoornia 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.
WBetula leopoldae is an extinct species of birch in the family Betulaceae. The species is known from fossil leaves, catkins, and inflorescences found in the early Eocene deposits of northern Washington state, United States, and similar aged formations in British Columbia, Canada. The species is placed as basal in Betula, either as a stem group species, or an early divergent species.
WCimbrophlebia is an extinct genus of Mecoptera which existed from the Jurassic to the Eocene period.
WComptonia columbiana is an extinct species of sweet fern in the flowering plant family Myricaceae. The species is known from fossil leaves found in the early Eocene deposits of central to southern British Columbia, Canada, plus northern Washington state, United States, and, tentatively, the late Eocene of Southern Idaho and Earliest Oligocene of Oregon, United States.
WCorylopsis reedae is an extinct species of flowering plant in the family Hamamelidaceae known from fossil leaves found in the early Eocene Klondike Mountain Formation deposits of northern Washington state. C. readae is one of the oldest occurrences of the winter-hazel genus Corylopsis, which includes between seven and thirty species, all found in Asia. Fossils from two other occurrences are of similar age to C. readae, with Paleocene specimens from Greenland being placed in the form taxon Corylopsiphyllum and an Eocene Alaskan fossil being included in Corylopsis without species placement.
WCorylus johnsonii is an extinct species of hazel 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. johnsonii is the oldest definite species in the genus Corylus.
WDinokanaga is a small genus of scorpionfly belonging to the extinct family Dinopanorpidae. The six species D. andersoni, D. dowsonae, D. hillsi, D. sternbergi, D. webbi, and D. wilsoni have all been recovered from Eocene fossil sites in British Columbia, Canada, and Washington state, United States.
WDipteronia is a genus with two living and one extinct species in the soapberry family Sapindaceae. The living species are native to central and southern China, while the fossil species is found in Middle Paleocene to Early Oligocene sediments of North America and China.
WDipteronia brownii is an extinct species in the soapberry family (Sapindaceae) described in 2001. Fossils of D. brownii are known from stratigraphic formations in North America and Asia ranging in age between Paleocene to Early Oligocene.
WEorpidae is a small family of extinct insects in the scorpionfly order, Mecoptera, which contains a single genus, Eorpa. Three Eocene age species found in Western North America have been placed into the genus: E. elverumi, E. jurgeni, and E. ypsipeda.
WEucommia montana is an extinct species of flowering plant in the family Eucommiaceae. E. montana is known from fossil fruits found in Eocene deposits of the northwestern United States southeastern British Columbia south to Oregon and east to Montana and Colorado. E. montana is one of five described fossil species from North America assigned to the modern genus Eucommia. The other species are E. constans, E. eocenica, E. jeffersonensis, and E. rowlandii.
WFlorissantia is an extinct genus of flowering plants in the Malvaceae subfamily Sterculioideae known from western North America and far eastern Asia. Flower, fruit, and pollen compression fossils have been found in formations ranging between the Early Eocene through to the Early Oligocene periods. The type species is Florissantia speirii and three additional species are known, Florissantia ashwillii, Florissantia quilchenensis, and Florissantia sikhote-alinensis.
WFothergilla malloryi is an extinct species of flowering plant in the family Hamamelidaceae known from fossil leaves found in the early Eocene Klondike Mountain Formation deposits of northern Washington state. The F. malloryi leaves are the earliest appearance in the fossil record of a member of the witchalder genus Fothergilla, which includes the living species F. gardenii, and F. major, both of which are native to the southeastern United States. The genus also includes three or four other fossil species with two Asian Miocene species, F. viburnifolia from China, F. ryozenensis from Japan along with one Miocene North American species, F. praeolata of Oregon. Fothergilla durhamensis described from Eocene sediments in King County, Washington is considered dubious in placement, and it was transferred to the genus Platimeliphyllum by Huegele et al. (2021).
WGinkgo dissecta is an extinct ginkgo species in the family Ginkgoaceae described from a series of isolated fossil leaves. The species is known from Early Eocene sediments exposed in the province of British Columbia, Canada, and Washington, USA. It is one of two Ginkgo species found at the Washington and British Columbia sites.
WHiodon 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.
WLangeria is an extinct genus of flowering plants in the family Hamamelidaceae, commonly known as the witch-hazel family, containing the solitary species Langeria magnifica. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States and similar aged formations in British Columbia, Canada.
WMetanephrocerus is an extinct genus of big-headed flies in the dipteran subfamily Protonephrocerinae, for which it is one of only two genera. The genus contains four described species, Metanephrocerus belgardeae, M. collini, M. groehni, and M. hoffeinsorum. Metanephrocerus is known from a group of Middle Eocene fossils which were found in Europe and a single early Eocene fossil from North America.
WMetasequoia occidentalis is an extinct redwood species of the family Cupressaceae that is found as fossils throughout the Northern Hemisphere. It is one of three extinct species of Metasequoia that are currently recognized as valid.
WMyrmeciites is an extinct form genus of bulldog ants in the subfamily Myrmeciinae of the family Formicidae, which contains three described species and two fossils not placed beyond the genus level. Described in 2006 from Ypresian stage deposits, all three of the described species and one unplaced fossil are from British Columbia, Canada, while the second unplaced fossil is from Washington State, USA. These ants were large, with the largest specimens collected reaching 3 centimetres (1.2 in). The behaviour of these ants would have been similar to extant Myrmeciinae ants, such as solitary foraging, nesting either in the soil or trees, and leaving no pheromone trail to food sources. Due to the poor preservation of these ants, their phylogenetic position among Myrmeciinae is unclear, and no type species has been designated. These ants are classified as incertae sedis in Myrmeciinae, but some writers have classified it as incertae sedis within the insect order Hymenoptera. This reclassification, however, has not been accepted; instead, Myrmeciites remains in Myrmeciinae.
WNeoephemera antiqua is an extinct species of square-gill mayfly in the family Neoephemeridae that is known from early Eocene, Ypresian stage, lake deposits near the small community of Republic in Ferry County, Washington, USA.
WNuphar carlquistii is an extinct species of flowering plant in the family Nymphaeaceae related to the modern spatterdock, Nuphar advena. The species is known from fossil seeds and fruits found in the early Eocene deposits of northern Washington state, United States, and a similar aged formation in British Columbia, Canada.
WOrontium wolfei is an extinct golden-club species in the family Araceae described from a series of isolated fossil leaves. The species is known from Eocene sediments exposed in the state of Washington in the United States of America and the province of British Columbia in Canada. It is one of several extinct species placed in the living golden-club genus Orontium.
WPalaeopsychops is an extinct genus of lacewing in the moth lacewings family Ithonidae. The genus is known from Early Eocene fossils found in Europe, and North America and is composed of ten species. The ten species can be informally separated into two species groups based on veination of the forewings, the "European" and "North American" groups. When first described, the genus was placed in the family Psychopsidae, but later was moved to Polystoechotidae, which itself is now considered a subgroup of the moth lacewings.
WPentacentron is an extinct genus of flowering plant in the family Trochodendraceae, consisting of the single species Pentacentron sternhartae. The genus is known from fossil fruits found in the early Eocene deposits of northern Washington state, United States. P. sternhartae are possibly the fruits belonging to the extinct trochodendraceous leaves Tetracentron hopkinsii.
WPinus latahensis is an extinct species of conifer in the pine family Pinaceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States, and southern British Columbia, Canada.
WPseudolarix wehrii is an extinct species of golden larch in the pine family (Pinaceae). The species is known from early Eocene fossils of northern Washington state, United States, and southern British Columbia, Canada, along with late Eocene mummified fossils found in the Qikiqtaaluk Region, Nunavut, Canada.
WPteronepelys, 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.
WRhus boothillensis is an extinct species of flowering plant in the sumac family Anacardiaceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington State, United States. The species was first described from fossil leaves found in the Klondike Mountain Formation. Rhus boothillensis likely hybridized with the other Klondike Mountain formation sumac species Rhus garwellii, Rhus malloryi, and Rhus republicensis.
WRhus garwellii is an extinct species of flowering plant in the sumac family Anacardiaceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington State, United States. The species was first described from fossil leaves found in the Klondike Mountain Formation. R. garwellii likely hybridized with the other Klondike Mountain formation sumac species R. boothillensis, R. malloryi, and R. republicensis.
WRhus malloryi is an extinct species of flowering plant in the sumac family Anacardiaceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States. The species was first described from a series of isolated fossil leaves in shale. R. malloryi is one of four sumac species to be described from the Klondike Mountain Formation, and forms a hybrid complex with the other three species.
WSassafras hesperia is an extinct species of flowering plant in the family Lauraceae.
WTaxodium dubium is an extinct species of cypress in the genus Taxodium in the family Cupressaceae which lived from the Late Paleocene to the Pliocene in North America and Europe. The species was first described in 1823 by Kaspar Maria von Sternberg.
WTetracentron hopkinsii is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States and south Central British Columbia. The species was first described from fossil leaves found in the Allenby Formation. T. hopkinsii are possibly the leaves belonging to the extinct trochodendraceous fruits Pentacentron sternhartae.
WTilia 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.
WTrochodendron nastae is an extinct species of flowering plant in the family Trochodendraceae known from fossil leaves found in the early Eocene Ypresian stage Klondike Mountain Formation deposits of northern Washington state. T. nastae is one of the oldest members of the genus Trochodendron, which includes the living species T. aralioides, native to Japan, southern Korea and Taiwan and the coeval extinct species T. drachukii from the McAbee Fossil Beds near Cache Creek, British Columbia.
WTsukada is an extinct genus of flowering plant in the family Nyssaceae related to the modern "dove-tree", Davidia involucrata, containing the single species Tsukada davidiifolia. The genus 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.
WUlmus okanaganensis is an extinct species of flowering plant in the family Ulmaceae related to the modern elms. The species is known from fossil leaves, flowers, and fruits found in the early Eocene deposits of northern Washington state, United States and similar aged formations in British Columbia, Canada.