''Wessiea'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

morphogenus of

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...

not placed in a specific family. ''Wessiea'' is known from

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

and

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

age

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s found in Central

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

USA and Southern

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Canada. Two species are described in the morphogenus, ''W. oroszii'' and the type species ''W. yakimaensis''.

History and classification

The genus was first described from specimens of

silicified In geology, petrifaction or petrification () is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this proce ...

rhizomes In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

and frond bases in blocks of

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...

. The chert was recovered from the "Ho ho" site, one of the "county line hole" fossil localities north of

Interstate 82 Interstate 82 (I-82) is an Interstate Highway in the Pacific Northwest region of the United States that travels through parts of Washington and Oregon. It runs from its northwestern terminus at I-90 in Ellensburg, Washington, to its southeaste ...

Yakima County, Washington Yakima County is a county in the U.S. state of Washington. As of the 2020 census, its population was 256,728. The county seat and largest city is Yakima. The county was formed out of Ferguson County in January 1865 and is named for the Yakama t ...

. The "Ho ho" site works strata which is part of the Museum Flow Package within the interbeds of the Sentinel Bluffs Unit of the central Columbia Plateau N₂

Grande Ronde Basalt The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt grou ...

Columbia River Basalt Group The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt grou ...

. The Museum Flow Package interbeds, designated the type locality, are dated to the

middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

and are approximately 15.6 million years old. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen, rhizomes and fronds #1–3 and 3 E2 #1–3, are preserved in chert block 3A1 and housed in the

Burke Museum of Natural History and Culture The Burke Museum of Natural History and Culture (Burke Museum) is a natural history museum in Seattle, Washington, in the United States. Established in 1899 as the Washington State Museum, it traces its origins to a high school naturalist club fo ...

as specimen number "''UWBM 56441''". The paratype, number 3F1 #2 top on specimen "UWBM 56441", is a rhizome which shows root gaps, roots and frond bases. The specimens of chert were studied by

paleobotanist Paleobotany, which is also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeogr ...

s Kathleen B. Pigg of

Arizona State University Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...

and Gar W. Rothwell of

Ohio University Ohio University is a Public university, public research university in Athens, Ohio. The first university chartered by an Act of Congress and the first to be chartered in Ohio, the university was chartered in 1787 by the Congress of the Confeder ...

. Pigg and Rothwell published their 2001

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

for ''Wessiea yakimaensis'' in the ''

American Journal of Botany The ''American Journal of Botany'' is a monthly peer-reviewed scientific journal which covers all aspects of plant biology. It has been published by the Botanical Society of America since 1914. The journal has an impact factor of 3.038, as of 201 ...

''. In their type description they note the

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

for the generic name is in honor of

Wesley C. Wehr Wesley Conrad Wehr (April 17, 1929 – April 12, 2004) was an American paleontology, paleontologist and artist best known for his studies of Cenozoic paleobotany, fossil floras in western North America, the Stonerose Interpretive Center, and as ...

for his numerous contributions to Tertiary paleobotany of western North America. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''yakimaensis'', is a reference to the type locality in the Yakima Canyon. Pigg and Rothwell noted the similarity between ''Wessiea'' and both the modern genus ''

Diplazium ''Diplazium'' is a genus of ferns that specifically includes the approximately 400 known species of twinsorus ferns. The Greek root is ''diplazein'' meaning ''double'': the indusia in this genus lie on both sides of the vein. These ferns were ...

'' and the fossil genus '' Makotopteris''. The second species is known from ironstones of the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

age

Horseshoe Canyon Formation The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller. The Horseshoe Canyon Formation is part of th ...

, Alberta, recovered at the "Fred's site" locality. The fossils, housed in the

Royal Tyrrell Museum of Palaeontology The Royal Tyrrell Museum of Palaeontology (RTMP, and often referred to as the Royal Tyrrell Museum) is a palaeontology museum and research facility in Drumheller, Alberta, Canada. The museum was named in honour of Joseph Burr Tyrrell, and is sit ...

, were dissolved from the ironstone and embedded into a

bioplastic Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste, etc. Some bioplastics are obtained by processing directly from natural ...

for study. After embedding, the fossils were acid peeled by paleobotanists Rudolph Serbet and Gar W. Rothwell for study in thin section slides. Serbert and Rothell published the description of ''W. oroszii'' in a 2006 article. The specific epithet "oroszii" is a patronym honoring s Alfred Orosz, paleontologist for the Royal Tyrrell Museum, and discoverer of the species type locality.

Description

The morphogenus is defined by the rhizomes and attached frond bases preserved by permineralization. The stipe shows the presence of two hippocampiform vascular bundles and the dictyostele is composed of forking meristeles.

''W. oroszii''

The rhizomes of ''W. oroszii'' are erect in positioning and grow up to in diameter, larger than ''W. yakimaensis''. The dictyostele is made of five to seven oval meristeles and has a maximum diameter of . The frond bases are flattened on the upper sides and generally produced by the rhizomes in groups of two to four in a helical arrangement.

''W. yakimaensis''

''W. yakimaensis'' possesses rhizomes which are in diameter. The frond bases where preserved in the chert are in a distinct helical arrangement and diverge from the center of the arrangement in a recumbent positioning. The dictyostele is composed of four to five individual meristeles each being oval in outline. It is found in the chert blocks intertwined with the extinct '' Osmunda wehrii'' and anatomically preserved '' Anchistea virginica'', which still lives in the forests of eastern coastal

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

References

{{Taxonbar, from=Q7984155 † Wessiea Prehistoric plant genera Fossil taxa described in 2001 Miocene plants Campanian genus first appearances Langhian genus extinctions Extinct flora of North America † Prehistoric plants of North America