Paleoflora of the Eocene Okanagan Highlands

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 1970s. The noted richness of agricultural plant families in Republic and Princeton floras resulted in the term "Eocene orchards" being used for the paleofloras.

Paleoflora

The Eocene Okanagan Highlands hosted a diverse mix of temperate and tropical paleobiotic elements, with the forests having the first significant proportions of temperate plants in North America. The paleobotanical community was a mixture of plants found in subtropical evergreen and temperate deciduous forests. The noted richness of Rosaceae fossils along with other important agricultural plant families found in the Republic and Princeton floras, including the genera that contain modern apples, blackberries, cherries, and serviceberries resulted in Wes Wher and Donald Hopkins (1994) coining the term "Eocene orchards". Fossil evidence from both Sorbus/Crataegus and Rhus leaves in the Republic sites indicate the area was a center for species overlap and active hybridization events. == Extent ==

Extent

The majority of the lake deposits are compression fossils in lake bed sediments grouped informally into "Northern", "Central", and "Southern" sites. The Northern sites are composed of unnamed Ootsa Group formations which outcrop as the "Driftwood shales" near Smithers, British Columbia, sites now considered lost in the Quesnel, British Columbia area, There is debate as to the affiliation of the, now lost, Quesnel outcrops with the Greater Okanagan Highlands. Archibald et al. (2018) in the monograph overview of the Highlands Hymenoptera included them as part of the series. However the certainty for the placement was later questioned by Archibald and Cannings (2022) who opted to tentatively exclude Quesnel from the highlands while discussing the history of field collecting in the region. == Chert and amber ==

Chert and amber

& "Ashnola shales" interbedding Additionally two important non-compression biotas are present in the Eocene Okanagan Highlands. A permineralized chert flora, the Princeton Chert is found along the Similkameen River interbedded with coal deposits of the Ashnola shale unit, Allenby Formation known for anatomically preserved plants. In the Central sites, subbituminous coal of the Hat Creek Coal Formation around Hat Creek hosts an amber biota, the Hat Creek amber which preserves many small insects and plant fragments that would likely not be found in the compression biotas. == Diatoms ==

Diatoms

Two algae taxa of the protist order Ochrophyta have been described from the highlands, and are placed in the family Aulacoseiraceae, a member of the diatom order Bacillariophyceae,. The third algae is identified as a living paleoendemic Mallomonas species now restricted to warmer climates in North America and Europe. == Bryophytes ==

Bryophytes

A group of six mosses were described from the Allenby Formation by Kuc (1972,1974) representing the genera Ditrichites, and , with two species placed in the morphogenus . and George Poinar, Jr. et al. (1999) illustrated an undescribed specimen of moss entombed in Hat Creek Amber. == Lycophytes ==

Lycophytes

Both an undescribed member of the fossil quillwort genus Isoetites and the spikemoss genus Selaginella have been found in the Klondike Mountain Formation, while an additional fossil deemed Cf. Selaginella was later reported from the Allenby Formation. == Pteridophytes ==

Pteridophytes

Five species of ferns and fern relatives have been described from the compression biotas and an additional four compression taxa that have been tentatively identified to family or genus. A series of four additional ferns have been described from premineralized specimens in the Princeton Chert and a fifth taxon is identified to genus. Several fern specimens were briefly mentioned from Horsefly but no taxonomic assignment was made due to lack of reproductive vegetation. == Gymnosperms ==

Gymnosperms

Three major groups of gymnosperms are present in the Okanagan Highlands formations, with the most speciose being the pinophytes. The ginkgophytes are represented by two species of Ginkgo, while an undescribed Zamiaceae member is the sole cycadophyte. Cycadophytes Gingkophytes Conifers Cupressaceae Pinaceae Sciadopityaceae Taxaceae == Angiosperms ==

Angiosperms

Nymphaeales The basal angiosperms are represented by two Nymphaeales water-lily species Nuphar carlquistii from the Republic and Princeton shales, plus Allenbya collinsonae from the Princeton Chert. Wehr (1995) illustrated two fossils that were tentatively identified as fruits of the banana genus Ensete and the extinct myrtle genus Paleomyrtinaea respectively, however further fossil finds resulted in the re-identification of the first as a N. carlquistii rhizome section, and the second is a seed mass from the same water-lily. Magnoliids Monocots Pigg, Manchester, and DeVore (2023) gave brief descriptions of three monocots from Horsefly, labeling them as Monocot #1 (broad leaved), Monocot #2 (parallel veined), and Monocot #3 (parallel veined). They did not give any taxonomic possibilities for the affinities of the fossils. Eudicots "Basal eudicots" "Superasterids" "Superrosids" Fabids COM clade Fabids nitrogen‑fixing clade Malvids Saxifragales and basal Superrosids ==== Incertae sedis ==== == Fungi ==

Fungi

A number of fungi have been preserved within the Princeton Chert, though only three have been formally described as of 2024. The first instance of ectomycorrhizae in the fossil record was reported by LePage et al. (1997) who documented mycorrhizal rootlets associated with Pinus roots. == Taxa of uncertain modern identification ==

Taxa of uncertain modern identification

A number of taxa identified or described by Penhallow (1902, 1906, 1908) and Berry (1926) have not received much or any modern attention, resulting in uncertainty of taxon affiliation, identification, or synonymy. Many late 1800's to early 1900's identifications of Okanagan highlands fossils were made based on geologic age assumptions ranging between the Miocene to Pliocene, and often specimens were grouped into species bins for taxa first described from Europe. == References ==

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