Uhlia

Uhlia; Temporal range: Ypresian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Arecales
Family:	Arecaceae
Subfamily:	Coryphoideae
Tribe:	Trachycarpeae
Genus:	† Uhlia ; Erwin & Stockey
Species:	†U. allenbyensis
Binomial name
	†Uhlia allenbyensis; Erwin & Stockey

Last updated February 06, 2024

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 .

Distribution

Uhlia allenbyensis is known exclusively from the Princeton Chert, a fossil locality in British Columbia, Canada,^[1] which comprises an anatomically preserved flora of Eocene Epoch age, with rich species abundance and diversity. The chert is located in exposures of the Allenby Formation on the east bank of the Similkameen River, 8.5 km (5.3 mi) south of the town of Princeton, British Columbia.^[2]

Notable in conjunction with the coal seams of the Allenby Formation are sections of chert which formed during silica-rich periods. The rapid cyclical changes from coal to chert and back are not noted in any other fossil locality in the world. An estimated 49 coal/chert cycles are known, though the exact conditions for this process are not well understood. Silica-rich volcanic episodes in the region during deposition would have been needed for formation of the cherts, while slowly moving waters and gently subsiding terrains would be needed for the peats and fens to accumulate. Rates of organic deposition in swamps have been estimated at approximately 0.5–1 mm (0.020–0.039 in) in modern temperate climates, this suggests the time needed for each 10–20 cm (3.9–7.9 in) chert layer would be at least 100 years or more, with the full sequence of cycles taking place over no more than 15,000 years.^[3]

The Allenby Formation is one of the southernmost of the Eocene Okanagan Highlands lakes in British Columbia and second most southern site after the Klondike Mountain Formation of Republic, Washington, in northern Ferry County. In British Columbia, the formation is coeval to the Tranquille Formation, known from the McAbee Fossil Beds and Falkland site, the Coldwater Beds, known from the Quilchena site, and Driftwood Canyon Provincial Park. The highlands, including the Allenby Formation, have been described as one of the "Great Canadian Lagerstätten "^[4] based on the diversity, quality and unique nature of the biotas that are preserved. The highlands temperate biome preserved across a large transect of lakes recorded many of the earliest appearances of modern genera, while also documenting the last stands of ancient lines.^[4]

History and classification

The chert palm fossils were first briefly described in 1976 by James Basinger as part of his PhD thesis; however, due to the isolated nature of the leaf and petiole specimens known at that time, the fossils were not given specific taxonomic treatment. Additional collecting and examination of recovered chert blocks over the next decade and a half included additional palm fossils and allowed for in-depth study by paleobotanists Diane Erwin and Ruth Stockey in the early 1990s. Erwin and Stockey used cellulose acetate peels with hydrofluoric acid to create serial thin sections of the fossils for anatomical and cellular study. The microscope slides were accessioned into the University of Alberta palaeobotanical collections.^[1] The formal description of the new genus and species was published by Erwin and Stockey (1994) in the journal Palaeontographica Abteilung B , with the genus name Uhlia being chosen as a matronym honoring palm systematist Natalie Uhl in recognition of her work on palm taxonomy and the specific name allenbyensis coined from Allenby, British Columbia, the ghost town that the Allenby Formation takes its name from.^[1]

In the type description, U. allenbyensis was assigned to the palm subfamily Coryphoideae and tribe Corypheae based on the similarity in leaf and stem anatomy to the living genera Brahea , Rhapidophyllum , and Serenoa . Subsequently phylogenetic evaluation of Coryphoideae has led to tribe Corypheae being restricted to only the type genus, with all other former members being placed on other tribes, Cryosophileae ^[5] or Trachycarpeae.^[6]

Description

Uhlia allenbyensis was a rhizomatous palm, with roots growing from the lower side of stems and leaves from the upper side.^[1] The roots range between 4–10 mm (0.16–0.39 in) wide with a central stele. The root cortex displays a narrow innermost layer of cells, and a middle cortex with a aerenchymous structure. The stems show a periderm-like layer of cells having irregular to rectangular shape and organized into vertical rows. Underlying the periderm-like layer the stem tissues are grouped into three major zones. The innermost zone, the central region, extends from the stem center to the boundary point with the "B zone". The peripheral area of the central region displays both leaf traces and vascular groupings which were interpreted as inflorescence traces.^[1]

Paleoecology

Leaves of Uhlia allenbyensis show parasitism by the parasitic fungus Paleoserenomyces allenbyensis which invaded the leaf surface cells. These parasitized areas have been described as similar to modern "tar spot" infections on leaves. In some cells of P. allenbyensis the hyperparasitic fungus Cryptodidymosphaerites princetonensis was preserved, providing a firm fossil record for fungal hyperparasitism.^[7]

The low stature of U. allenbyensis has been likened to that of the modern saw palmetto Serenoa repens , a morphology consistent with its tribal placement. Palm beetle fossils are also found in the greater Okanagan highlands, both in the Tranquille Formation north of Princeton and in the Klondike Mountain Formation to the south. The beetles have been assigned to the Caryobruchus – Speciomerus genus group and are obligate parasites of palms in the tribes Cocoaceae, Coryphaea, Hyphorbeae, and Phoeniceae.^[8]

Paleoenvironment

The Princeton chert preserves an aquatic system with silica rich slow moving waters which was likely a peat fen ecosystem. While other fossil producing areas of the Allenby Formation are likely the product of deep water deposition and diatomite sedimentation, the chert layers originate from shallow waters, as evidenced by plant and animal fossils.^[3] The Okanagan Highland sites, such as the Princeton chert represent upland lake systems that were surrounded by a warm temperate ecosystem with nearby volcanism.^[4] The 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.^[9] 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 than 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 of 0.8 km (0.50 mi) but higher.^[9]

Estimates of the mean annual temperature have been derived from climate leaf analysis multivariate program (CLAMP) analysis and leaf margin analysis (LMA) of the Princeton paleoflora. The CLAMP results after multiple linear regressions for Princeton's gave a 5.1 °C (41.2 °F), and the LMA returned a mean annual temperature of 5.1 ± 2.2 °C (41.2 ± 4.0 °F). This is 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 Princeton suggest mean annual precipitation amount of 114 ± 42 cm (45 ± 17 in).^[9]

The warm temperate uplands floras of the Allenby Formation and greater highlands 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.^[10]

Related Research Articles

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The Princeton Chert is a fossil locality in British Columbia, Canada, which comprises an anatomically preserved flora of Eocene Epoch age, with rich species abundance and diversity. It is located in exposures of the Allenby Formation on the east bank of the Similkameen River, 8.5 km (5.3 mi) south of the town of Princeton, British Columbia.

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.

The Allenby formation is a sedimentary rock formation in British Columbia which was deposited during the Ypresian stage of the Early Eocene. It consists of conglomerates, sandstones with interbedded shales and coal. The shales contain an abundance of insect, fish and plant fossils known from 1877 and onward, while the Princeton Chert was first indented in the 1950's and is known from anatomically preserved plants.

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Comptonia 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.

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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.

Equisetum similkamense is an extinct horsetail species in the family Equisetaceae described from a group of whole plant fossils including rhizomes, stems, and leaves. The species is known from Ypresian sediments exposed in British Columbia, Canada. It is one of several extinct species placed in the living genus Equisetum.

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.

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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.

The paleofauna of the Eocene Okanagan Highlands consists of Early Eocene arthropods, vertebrates, plus rare nematodes and molluscs found in geological formations of the northwestern North American Eocene Okanagan Highlands. The highlands lake bed series' as a whole are considered one of the great Canadian Lagerstätten. The paleofauna represents that of a late Ypresian 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. Focus and more detailed descriptive work on the Okanagan Highlands site started in the last 1970's. Most of the highlands sites are preserved as compression-impression fossils in "shales", but also includes a rare permineralized biota and an amber biota.

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.

Cryptodidymosphaerites is an extinct monotypic genus of pleosporale fungus of uncertain family placement. When described it contained the single species Cryptodidymosphaerites princetonensis. The genus is solely known from the Early Eocene, Ypresian aged, Princeton Chert deposit of the Allenby Formation. Cryptodidymosphaerites is one of only three described fossil fungus species found in the Princeton Chert, and is a hyperparasite of Palaeoserenomyces allenbyensis, itself a tar spot-like parasite of the fossil palm Uhlia.

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.

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.

Allenbya is an extinct genus of water lilies in the family Nymphaceae containing a single species Allenbya collinsonae. The species is known from permineralized remains recovered from the Early Eocene Princeton Chert in British Columbia, Canada.

References

1 2 3 4 5 Erwin, D.M.; Stockey, R.A. (1994). "Permineralized monocotyledons from the middle Eocene Princeton chert (Allenby Formation) of British Columbia: Arecaceae". Palaeontographica Abteilung B. 234: 19–40.
↑ Miller, C. (1975). "Silicified cones and vegetative remains of Pinus from the Eocene of British Columbia". Contributions from the Museum of Paleontology, University of Michigan. 24 (10): 101–118.
1 2 Mustoe, G. (2010). "Cyclic sedimentation in the Eocene Allenby Formation of south-central British Columbia and the origin of the Princeton Chert fossil beds". Canadian Journal of Earth Sciences. 48 (1): 25–43. doi:10.1139/e10-085.
1 2 3 Archibald, S.; Greenwood, D.; Smith, R.; Mathewes, R.; Basinger, J. (2011). "Great Canadian Lagerstätten 1. Early Eocene Lagerstätten of the Okanagan Highlands (British Columbia and Washington State)". Geoscience Canada. 38 (4): 155–164.
↑ Stevens, P.F. (2015) [1st. Pub. 2001], Arecale-Angiosperm Phylogeny Website , retrieved 22 December 2021
↑ Greenwood, D.; Conran, J. (2020). "Fossil coryphoid palms from the Eocene of Vancouver, British Columbia". International Journal of Plant Sciences. 181 (2): 224–240. doi:10.1086/706450. S2CID 208587364.
↑ Currah, RA; Stockey, RA; LePage, BA (1998). "An Eocene tar spot on a fossil palm and its fungal hyperparasite". Mycologia. 90 (4): 667–673. doi:10.2307/3761225. JSTOR 3761225.
↑ Archibald, S.B.; Morse, G.; Greenwood, D.R.; Mathewes, R.W. (2014). "Fossil palm beetles refine upland winter temperatures in the Early Eocene Climatic Optimum". Proceedings of the National Academy of Sciences. 111 (22): 8095–8100. Bibcode:2014PNAS..111.8095A. doi: 10.1073/pnas.1323269111 . PMC 4050627 . PMID 24821798.
1 2 3 Greenwood, D.R.; Archibald, S.B.; Mathewes, R.W; Moss, P.T. (2005). "Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape" (PDF). Canadian Journal of Earth Sciences. 42 (2): 167–185. Bibcode:2005CaJES..42..167G. doi:10.1139/e04-100.
↑ DeVore, M. L.; Nyandwi, A.; Eckardt, W.; Bizuru, E.; Mujawamariya, M.; Pigg, K. B. (2020). "Urticaceae leaves with stinging trichomes were already present in latest early Eocene Okanogan Highlands, British Columbia, Canada". American Journal of Botany. 107 (10): 1449–1456. doi: 10.1002/ajb2.1548 . PMID 33091153. S2CID 225050834.

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[Uhlia1994-1] 1 2 3 4 5 Erwin, D.M.; Stockey, R.A. (1994). "Permineralized monocotyledons from the middle Eocene Princeton chert (Allenby Formation) of British Columbia: Arecaceae". Palaeontographica Abteilung B. 234: 19–40.

[2] Miller, C. (1975). "Silicified cones and vegetative remains of Pinus from the Eocene of British Columbia". Contributions from the Museum of Paleontology, University of Michigan. 24 (10): 101–118.

[Mustoe2010-3] 1 2 Mustoe, G. (2010). "Cyclic sedimentation in the Eocene Allenby Formation of south-central British Columbia and the origin of the Princeton Chert fossil beds". Canadian Journal of Earth Sciences. 48 (1): 25–43. doi:10.1139/e10-085.

[GCL2011-4] 1 2 3 Archibald, S.; Greenwood, D.; Smith, R.; Mathewes, R.; Basinger, J. (2011). "Great Canadian Lagerstätten 1. Early Eocene Lagerstätten of the Okanagan Highlands (British Columbia and Washington State)". Geoscience Canada. 38 (4): 155–164.

[APGWEB-5] Stevens, P.F. (2015) [1st. Pub. 2001], Arecale-Angiosperm Phylogeny Website , retrieved 22 December 2021

[G&Cpalms2020-6] Greenwood, D.; Conran, J. (2020). "Fossil coryphoid palms from the Eocene of Vancouver, British Columbia". International Journal of Plant Sciences. 181 (2): 224–240. doi:10.1086/706450. S2CID 208587364.

[Currah1998-7] Currah, RA; Stockey, RA; LePage, BA (1998). "An Eocene tar spot on a fossil palm and its fungal hyperparasite". Mycologia. 90 (4): 667–673. doi:10.2307/3761225. JSTOR 3761225.

[palmbeetles2014-8] Archibald, S.B.; Morse, G.; Greenwood, D.R.; Mathewes, R.W. (2014). "Fossil palm beetles refine upland winter temperatures in the Early Eocene Climatic Optimum". Proceedings of the National Academy of Sciences. 111 (22): 8095–8100. Bibcode:2014PNAS..111.8095A. doi: 10.1073/pnas.1323269111 . PMC 4050627 . PMID 24821798.

[Greenwood2005-9] 1 2 3 Greenwood, D.R.; Archibald, S.B.; Mathewes, R.W; Moss, P.T. (2005). "Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape" (PDF). Canadian Journal of Earth Sciences. 42 (2): 167–185. Bibcode:2005CaJES..42..167G. doi:10.1139/e04-100.

[DeVore2020-10] DeVore, M. L.; Nyandwi, A.; Eckardt, W.; Bizuru, E.; Mujawamariya, M.; Pigg, K. B. (2020). "Urticaceae leaves with stinging trichomes were already present in latest early Eocene Okanogan Highlands, British Columbia, Canada". American Journal of Botany. 107 (10): 1449–1456. doi: 10.1002/ajb2.1548 . PMID 33091153. S2CID 225050834.

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