Dennstaedtia christophelii

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Dennstaedtia christophelii
Temporal range: Eocene (Ypresian)
~51–49  Ma
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Dennstaedtia christophelii holotype SRIC SR 13-004-001 A img1.tif
Holotype fossil
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Dennstaedtiaceae
Genus: Dennstaedtia
Species:
†D. christophelii
Binomial name
†Dennstaedtia christophelii
Pigg et al.

Dennstaedtia christophelii is an extinct species of fern in the family Dennstaedtiaceae related to the modern hayscented ferns. The species is known from fossil fronds found in early Eocene sites of northern Washington state, United States and central British Columbia, Canada. The species is suggested to be closest to a Neotropical "Patania" clade and specifically the species Dennstaedtia producta and Dennstaedtia mathewsii .

Contents

Distribution

Dennstaedtia christophelii fossils have been recovered from the two sites in the Eocene Okanagan Highlands of Central British Columbia and northeast central Washington state. Two of the described specimens are from the Klondike Mountain Formation in Northern Ferry County, Washington, but recovered from separate outcrops, the "Boot Hill" site B4131 in Republic, and "S100" just to the Northwest of Republic. The third known specimen is from the Tranquille Formation's Falkland site on Estekwalan Mountain in the Columbia–Shuswap region of South Central British Columbia. [1]

History and classification

Fern fossils of the subclass Polypodiidae, commonly called leptosporangiate ferns, have been reported in the Eocene Okanagan Highlands since the late 1890s, and the first fertile fond material report came from Edward W. Berry (1926). [1] More recently the Falkland specimen was first figured in Robin Y. Smiths 2011 PhD dissertation. The Republic and Falkland fossils were studied subsequently by a group of paleobotanists led by Kathleen B. Pigg, with the 2021 type description of the species being published in the International Journal of Plant Sciences . [1] They designated three type specimens at the time of publication, the holotype "SR 13-004-001 A&B" and paratype "SR 13-007-003 A&B" which were both accessioned in the Stonerose Interpretive Center paleobotanical collection, while the second paratype "US960-10656" was part of the Royal British Columbia Museum paleontology collection. The holotype and paratype 1 were collected from the Klondike Mountain Formation, at site "B4131" and "S100" respectively, while paratype 3 was collected from "Unit 1" of the Falkland sites Tranquille Formation exposure. The team coined the specific epithet christophelii as a patronym honoring David C. Christophel who was a mentor to two of the research team, David Greenwood and James Basinger. [1]

The group placed the new species into the modern genus Dennstaedtia based on the specific placement and shape of the preserved sori indusia. The placement of the fossil sori are along the pinnae edges, while the sori of Microlepia are along the pinnae sinuses and Pteridium sori are produced as continual stripe an not as individuals. [1] Hypolepis has lost the upper indusia while the fossils have full globose indusia on both the upper and lower surfaces. These features narrow the generic placement to Dennstaedtia. The genus as of 2022 included approximately 55 species which are mostly found in the tropics globally, with the exception of continental Africa. Of the species in Dennstaedtia, D. christophelii is most similar in its known morphology to two neotropical species D. mathewsii and D. producta . [1] Both species are native to South America, with D. producta restricted to Colombia [2] while D. mathewsii is known from both Bolivia and Colombia. [3] The Okanagan Highlands species differs from the extant species in having fully spherical sori, while both modern species have subglobose sori. [1]

The age of D. christophelii fossils has been used in several molecular phylogeny studies of dennstaedtiinean ferns. An investigation of the suborder Dennstaedtiineae by Jin-Mei Lu et al. (2022) employed the Ypresian age of the species as part of its divergence time calibrations, specifically for the crown group Dennstaedtioideae genera. [4] A year later, a study by Luz Triana-Moreno et al (2023) on the subfamily Dennstaedtioideae reconfirmed the placement of D. christophelii and noted the Ypresian age fell between two suggested divergence times for crown group Dennstaedtia. [5]

Description

Dennstaedtia christophelii is known only from leaf frond fossils, and as such the rhizomes frond anatomy, and spore morphology is unknown. The known fronds are all incomplete and range from 4.5–6.8 cm (1.8–2.7 in) in lengths, with the overall largest frond length unknown. The fronds have pinnation that grades from having leaflets fully divided at the base to fused leaflets approaching's the frond apices. [1] The individual pinnae are widely spaced along the rachis and range between 5–9 mm (0.20–0.35 in) by 3–5 mm (0.12–0.20 in) wide and progress from subopposite placement basally to alternate nearer the frond apex. They have a petiole which connects from rachis to the squared off base formed by the basal most pinnule pair of the lanceolate pinnae. Due to preservation, the lack of any induments along the pinnae is probable, but not conclusively determinable. [1]

There are between 3 and 10 pinnules, 4-5 of which are separate basally, while the apical pinnules are fused. Each of the pinnules are oblong in outline with basal margins that are sessile along the petioles. The margins of each vary from shallowly crenated into fully but shallowly lobed. Each pinnule is vascularized with a vein that forks one or two times after entering before finally ending near the leaf margin, and where they are present, in the globose sori. [1] Sori range between 0.5–1 mm (0.020–0.039 in) wide and are surrounded by a cup-shaped indusia placed as groupings along the leaf margin and extending beyond the marginal edge. Where preserved the sori are comprised of numerous sporangia. Within each sporangia, the annulus is comprised of between six and seven cells that are tangentially lengthened to facilitate the sporangium opening in favorable conditions. Examination of the fossils via an environmental scanning electron microscope showed that most of the leaf matter was of poor preservation and fragmentary, however the annulus tissues were distinctly well preserved. [1]

Paleoecology

Dennstaedtia christophelii is likely to have been an understory plant in the angiosperm dominated forests surrounding the lake systems. [1]

Paleoenvironment

Both Okanagan Highlands formations represent upland lake systems that were surrounded by a warm temperate ecosystem [1] with nearby volcanism [6] dating from during and just after the early Eocene climatic optimum. 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. [7] The 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. [7]

Estimates of the mean annual temperature have been derived from climate leaf analysis multivariate program (CLAMP) analysis of the Republic paleoflora, and leaf margin analysis (LMA) of both paleofloras. The CLAMP results after multiple linear regressions for Republic gave a mean annual temperature of approximately 8.0 °C (46.4 °F), with the LMA giving 9.2 ± 2.0 °C (48.6 ± 3.6 °F). [7] LMA results from Falkland returned the higher 10.0 ± 2.2 °C (50.0 ± 4.0 °F), slightly higher than seen at Republic, and CLAMP analysis gave an overall mean annual temperature of 12.8 ± 1.2 °C (55.0 ± 2.2 °F). A bioclimatic-based estimate based on modern relatives of the taxa found at each site suggested mean annual temperatures around 13.5 ± 2.2 °C (56.3 ± 4.0 °F) for Republic and 14.7 ± 2.1 °C (58.5 ± 3.8 °F) for Falkland. [7] These 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 Republic and Falkland suggest mean annual precipitation amounts of 115 ± 39 cm (45 ± 15 in) and 105 ± 48 cm (41 ± 19 in) respectively. [7]

Related Research Articles

<span class="mw-page-title-main">Frond</span> Collection of leaflets on a plant

A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the large leaves of cycads, as well as palms (Arecaceae) and various other flowering plants, such as mimosa or sumac. "Frond" is commonly used to identify a large, compound leaf, but if the term is used botanically to refer to the leaves of ferns and algae it may be applied to smaller and undivided leaves.

<span class="mw-page-title-main">Dennstaedtiaceae</span> Family of ferns

Dennstaedtiaceae is one of fifteen families in the order Polypodiales, the most derived families within monilophytes (ferns). It comprises 10 genera with ca 240 known species, including one of the world's most abundant ferns, Pteridium aquilinum (bracken). Members of the order generally have large, highly divided leaves and have either small, round intramarginal sori with cup-shaped indusia or linear marginal sori with a false indusium formed from the reflexed leaf margin. The morphological diversity among members of the order has confused past taxonomy, but recent molecular studies have supported the monophyly of the order and the family. The reclassification of Dennstaedtiaceae and the rest of the monilophytes was published in 2006, so most of the available literature is not updated.

<i>Cyathea affinis</i> Species of plant

Cyathea affinis is a variable species of tree fern native to Fiji, Samoa, the Cook Islands, Austral Islands, Tahiti, and the Marquesas Islands. The trunk of this plant is erect and 2–6 m tall. Fronds are bipinnate and 2–3 m in length. The rachis and stipe are pale to brown in colour, or flushed with red towards the pinnule rachis. The stipe is sparsely covered in narrow basal scales, which are pale to dark and have broad fragile edges. Characteristically of this species, the lowest one or two pairs of pinnae may be slightly reduced and occur towards the base of the stipe. Sori are located near the pinnule midvein and are partially or fully covered by indusia, which open towards the pinnule margin.

Gymnosphaera atropurpurea, synonyms Alsophila atropurpurea and Cyathea atropurpurea, is a species of tree fern native to the islands of Luzon, Mindanao, Leyte and Mindanao in the Philippines, where it grows in forest at above 1000 m. The erect trunk is slender and may be up to 3 m tall. Fronds are bipinnate and 1–2 m long. Characteristically of this species, the final pair of pinnae are usually reduced and occur towards the base of the stipe. These, along with the stipe bases, are persistent and retained around the trunk long after withering. The stipe itself is dark and covered with scales, which are either small, dull and brown or large, dark and glossy. Sori occur near the midvein of fertile pinnules and lack indusia. Fertile pinnules are notably smaller than sterile ones.

Gymnosphaera commutata is a Malesian species of tree fern found in wet and swampy forests.

<i>Dennstaedtia</i> Genus of ferns

Dennstaedtia is a mostly tropical and subtropical group of ferns described as a genus in 1801. Hayscented fern, or cup ferns, are common names for some species in this genus. It includes 58 species native to the tropical Americas, Madagascar, southern and eastern Asia, Australia, New Guinea, and the Pacific Islands.

<i>Tilia johnsoni</i> Extinct species of flowering plant

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.

<i>Asplenium bradleyi</i> Species of fern in the family Aspleniaceae

Asplenium bradleyi, commonly known as Bradley's spleenwort or cliff spleenwort, is a rare epipetric fern of east-central North America. Named after Professor Frank Howe Bradley, who first collected it in Tennessee, it may be found infrequently throughout much of the Appalachian Mountains, the Ozarks, and the Ouachita Mountains, growing in small crevices on exposed sandstone cliffs. The species originated as a hybrid between mountain spleenwort and ebony spleenwort ; A. bradleyi originated when that sterile diploid hybrid underwent chromosome doubling to become a fertile tetraploid, a phenomenon known as allopolyploidy. Studies indicate that the present population of Bradley's spleenwort arose from several independent doublings of sterile diploid hybrids. A. bradleyi can also form sterile hybrids with several other spleenworts.

<i>Myriopteris tomentosa</i> Species of fern

Myriopteris tomentosa, formerly known as Cheilanthes tomentosa, is a perennial fern known as woolly lipfern. Woolly lipfern is native to the southern United States, from Virginia to Arizona and Georgia, and Mexico.

<i>Myriopteris lanosa</i> Species of fern

Myriopteris lanosa, the hairy lip fern, is a moderately-sized fern of the eastern United States, a member of the family Pteridaceae. Its leaves and stem are sparsely covered in hairs, but lack scales, hence its common name. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in shallow, dry, soil, often in rocky habitats.

<i>Myriopteris alabamensis</i> Species of fern

Myriopteris alabamensis, the Alabama lip fern, is a moderately-sized fern of the United States and Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its leaves have a few hairs on upper and lower surfaces, or lack them entirely. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes as Cheilanthes alabamensis until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in shade on limestone outcrops.

Myriopteris aemula, the Texas lip fern or rival lip fern, is a moderately-sized fern of Texas and Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its leaves have a few hairs on upper and lower surfaces, or lack them entirely. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes as Cheilanthes aemula until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on limestone rock.

Myriopteris allosuroides is a moderately-sized fern of Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its rachides are grooved on the upper surface and largely free of hairs or scales. One of the cheilanthoid ferns, it was usually classified in the genera Cheilanthes or Pellaea until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on dry, rocky slopes over acidic, particularly basaltic, rock.

Baja is a genus of ferns in the subfamily Cheilanthoideae of the family Pteridaceae with a single species Baja brandegeei, synonym Cheilanthes brandegeei. The species is native to Baja California including the offshore Cedros Island, Mexico.

<i>Comptonia columbiana</i> Extinct species of sweet fern

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.

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.

<i>Fagus langevinii</i> Fossil species of beech tree

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.

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.

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 Eocene Ypresian stage and has only been found at the type locality in east central British Columbia.

Dickwhitea is an extinct morphogenus of lady fern containing a single morphospecies Dickwhitea allenbyensis. The species is known from permineralized remains recovered from the Princeton Chert in British Columbia, Canada. Rhizomes of Dickwhitea are noted for having a sympodial vascular architecture notably similar to Ginkgo biloba and Sequoia sempervirens.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Pigg, K. B.; DeVore, M. L.; Greenwood, D. R.; Sundue, M. A.; Schwartsburd, P.; Basinger, J. F. (2021). "Fossil Dennstaedtiaceae and Hymenophyllaceae from the Early Eocene of the Pacific Northwest". International Journal of Plant Sciences. 182 (9): 793–807. doi:10.1086/715633. S2CID   239036762.
  2. ↑ "Dennstaedtia producta Mett". Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 2 December 2023.
  3. ↑ "Dennstaedtia mathewsii C.Chr". Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 2 December 2023.
  4. ↑ Lu, J.M.; Du, X.Y.; Kuo, L.Y.; Ebihara, A.; Perrie, L.R.; Zuo, Z.Y.; Shang, H.; Chang, Y.H.; Li, D.Z. (2022). "Plastome phylogenomic analysis reveals evolutionary divergences of Polypodiales suborder Dennstaedtiineae". BMC Plant Biology. 22 (511): 511. doi: 10.1186/s12870-022-03886-1 . PMC   9628275 . PMID   36319964.
  5. ↑ Triana-Moreno, L.A.; Yañez, A.; Kuo, L.Y.; Rothfels, C.J.; Pena, N.T.L.; Schwartsburd, P.B.; Sundue, M. (2023). "Phylogenetic revision of Dennstaedtioideae (Dennstaedtiaceae: Polypodiales) with description of Mucura, gen. nov". Taxon. 72 (1): 20–46. doi: 10.1002/tax.12858 .
  6. ↑ 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.
  7. 1 2 3 4 5 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". Canadian Journal of Earth Sciences. 42 (2): 167–185. Bibcode:2005CaJES..42..167G. doi:10.1139/e04-100.
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