Concavistylon

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Concavistylon
Temporal range: Langhian
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Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Trochodendrales
Family: Trochodendraceae
Genus:† Concavistylon
Species:
†C. kvacekii
Binomial name
†Concavistylon kvacekii
Manchester, Pigg, & DeVore, 2018

Concavistylon is an extinct genus of flowering plant in the family Trochodendraceae comprising a single species Concavistylon kvacekii. The genus is known from fossils found in Middle Miocene deposits of central Oregon. A second species "Concavistylon" wehrii was originally placed in Concavistylon, but subsequently moved to a new genus Paraconcavistylon in 2020.

Contents

Distribution and paleoenvironment

Concavistylon kvacekii fossils were found in the Moose Mountain Flora, formerly called the Cascadia flora or Menagerie Wilderness flora, of Linn County, Oregon. The flora is included in the Little Butte Volcanic series outcropping near the town of Cascadia in the central Oregon Cascades. Work on the flora by paleobotanist Jack Wolfe in 1964 gave an estimated age of Early Miocene, this was later revised by Wolfe and Tanai in 1987 to a Late Oligocene estimation. [1] In the descriptive paper naming Concavistylon Manchester et al. reported that radioisotope dating of plagioclase crystals collected by Robert Rosé from the fossiliferous horizon of the Moose Mountain flora had been performed. Using crystals obtained from tuffaceous sandstones, Argon–argon dating provided an age of 14.91 ± 0.23 Ma placing the flora as Middle Miocene Langhian stage. [2] C. kvacekii is found associated with species such as Acer cascadense , Acer smileyi , Ozakia emryi , [3] Trochodendron postnastae , and Trochodendron rosayi . [2]

Taxonomy and phylogeny

The type species holotype was originally collected during the 1950s by Eleanor Gordon Thompson and donated to the University of California Museum of Paleontology in Berkeley, California as specimen UCMP 151875. [2] Study of the fossil by paleobotanists Steven Manchester, Kathleen Pigg, and Melanie DeVore, resulted in the description of Concavistylon kvacekii published 60 years later in 2018. [2] The etymology of the genus name was explained, while the specific name "kvacekii" was coined as a patronym honoring Czech paleobotanist Zlatko Kvaček. [2]

In a paper published nearly concurrently, a second species was described and placed into the genus as Concavistylon wehrii. The new species was from the older Ypresian age Klondike Mountain Formation of northeastern Washington and McAbee Fossil Beds in central British Columbia. [4] The description of Paleocene trochodendraceous fossils from Wyoming and a phylogenetic analysis of two living and four extinct genera indicated that Concavistylon was not monophyletic. [5] Based on the pendulous nature of "C." wehrii inflorescences, which are distinct from the erect inflorescences of C. kvacekii, the new genus Paraconcavistylon was erected with "C." wehrii as the type species. [5]

Trochodendraceae

Trochodendron

Eotrochion polystylum

Concavistylon kvacekii

Paraconcavistylon wehrii

Pentacentron sternhartae

Tetracentron

Description

The fruiting bodies of Concavistylon kvacekii are simple 40–51 mm (1.6–2.0 in) long racemes with a stout 1.3–1.8 mm (0.051–0.071 in) central stem. The fruits are either subsessile or born on very short pedicels. Each fruit is composed of between four and six carpels and range between 2.5–3.4 mm (0.098–0.134 in) wide by 3–4 mm (0.12–0.16 in) tall. There are between four and five persistent styles that curve upwards towards the fruit apex, a feature not seen in either Tetracentron or Trochodendron where the styles curve out and down from the fruit. The fruits open in a four to six ray dehiscence split. [2]

Related Research Articles

<i>Trochodendron</i> Genus of flowing plants in the family Trochodendraceae

Trochodendron is a genus of flowering plants with one living species, Trochodendron aralioides, and six extinct species known from the fossil record. It was often considered the sole genus in the family Trochodendraceae, though botanists now also include the distinct genus Tetracentron in the family.

<span class="mw-page-title-main">Trochodendraceae</span> Family of flowering plants

Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species along with up to five additional extinct genera and a number of extinct species. The living species are native to south east Asia. The two living species both have secondary xylem without vessel elements, which is quite rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention.

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<span class="mw-page-title-main">Klondike Mountain Formation</span>

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Acer clarnoense is an extinct maple species in the family Sapindaceae described from a series of isolated fossil leaves and samaras. The species is known from the late Eocene sediments exposed in the state of Oregon in the US. It is one of several extinct species placed in the living section Macrantha.

<span class="mw-page-title-main">McAbee Fossil Beds</span>

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Acer palaeorufinerve is an extinct maple species in the family Sapindaceae described from series of isolated fossil samaras and leaves. The species was described from Miocene to Pliocene aged fossils found in Japan and is known from Korean fossils and Miocene sediments exposed in the state of Alaska, USA. It is one of several extinct species placed in the living section Macrantha.

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<i>Shirleya</i> Extinct genus of plants

Shirleya is an extinct genus in the crape myrtle family, Lythraceae, which contains a single species, Shirleya grahamae. The genus and species are known from Middle Miocene fossils found in Central Washington.

<i>Pentacentron</i> Extinct genus of Trochodendralean plant

Pentacentron 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.

<i>Tetracentron hopkinsii</i> Extinct species of flowering plant

Tetracentron 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.

Trochodendron postnastae is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossils found in Middle Miocene deposits of central Oregon. T. postnastae are possibly the leaves belonging to the extinct trochodendraceous fruits Trochodendron rosayi.

Acer cascadense is an extinct maple species in the family Sapindaceae described from a series of isolated fossil samaras. The species is known from fossils found in Middle Miocene deposits of central Oregon. It is one of several extinct species placed in the living Acer section Negundo.

Trochodendron rosayi is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossils found in Middle Miocene deposits of central Oregon. T. rosayi are possibly the fruits belonging to the extinct trochodendraceous leaf species Trochodendron postnastae.

Paraconcavistylon is an extinct genus of flowering plant in the family Trochodendraceae comprises a single species, Paraconcavistylon wehrii. The genus is known from fossil fruits and leaves found in the early Eocene deposits of northern Washington state, United States, and southern British Columbia, Canada. The species was initially described as a member of the related extinct genus Concavistylon as "Concavistylon" wehrii, but subsequently moved to the new genus Paraconcavistylon in 2020 after additional study.

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.

<i>Pteronepelys</i> Fossil genus of plants

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.

References

  1. ↑ Wolfe, J.A.; Tanai, T. (1987). "Systematics, Phylogeny, and Distribution of Acer (maples) in the Cenozoic of Western North America". Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and Mineralogy. 22 (1): 40, 46, 47.
  2. 1 2 3 4 5 6 Manchester, S.; Pigg, K. B.; Devore, M. L. (2018). "Trochodendraceous fruits and foliage in the Miocene of western North America" (PDF). Fossil Imprint. 74 (1–2): 45–54. doi: 10.2478/if-2018-0004 . S2CID   133942808.
  3. ↑ Manchester, S. R.; Uemura, K. (2013). "Ozakia, a new genus of winged fruit shared between the Miocene of Japan and western North America". Journal of Plant Research. 127 (2): 187–92. doi:10.1007/s10265-013-0602-2. PMID   24306324. S2CID   22167161.
  4. ↑ Manchester, S.; Pigg, K. B.; Kvaček, Z; DeVore, M. L.; Dillhoff, R. M. (2018). "Newly recognized diversity in Trochodendraceae from the Eocene of western North America". International Journal of Plant Sciences. 179 (8): 663–676. doi:10.1086/699282. S2CID   92201595.
  5. 1 2 Manchester, S. R.; Kvaček, Z.; Judd, W. S. (2020). "Morphology, anatomy, phylogenetics and distribution of fossil and extant Trochodendraceae in the Northern Hemisphere". Botanical Journal of the Linnean Society. 195 (3): 467–484. doi: 10.1093/botlinnean/boaa046 .
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