''Paleopanax'' 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 ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the Ginseng and

Ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and ...

family,

Araliaceae The Araliaceae are a family of flowering plants composed of about 43 genera and around 1500 species consisting of primarily woody plants and some herbaceous plants. The morphology of Araliaceae varies widely, but it is predominantly distinguisha ...

, containing the single species ''Paleopanax oregonensis''. The species is solely known from the middle Eocene sediments exposed in north central

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

and was first described from a series of isolated

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 ...

fruits in

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

History and classification

''Paleopanax oregonensis'' has been identified from a single location in the

Clarno Formation Clarno may refer to: Locations * Clarno, Oregon * Clarno, Wisconsin ** Clarno (community), Wisconsin *Clarno Township, Lake County, South Dakota Lake County is a county in the U.S. state of South Dakota. As of the 2020 United States Census, t ...

, the Clarno nut beds, type locality for both the formation and the species. The nut beds are approximately east of the unincorporated community of

Clarno, Oregon Clarno is an unincorporated community in Wasco County, Oregon, United States. It is located along Oregon Route 218 near the John Day River. History The community was named after Andrew Clarno, an early settler. The Clarno post office was estab ...

, and currently considered to be middle Eocene in age, based on averaging zircon fission track

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

which yielded an age of 43.6 and 43.7 ± 10

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

and argon–argon dating

which yielded a 36.38 ± 1.31 to 46.8 ± 3.36 Mya date. The average of the dates resulted in an age range of 45 to 43 Mya. The beds are composed of silica and calcium carbonate cemented

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

aceous sandstones, siltstones, and conglomerates which preserve either a lake delta environment, or alternatively periodic floods and volcanic mudflows preserved with hot spring activity. The genus and species was described from a series of

type specimens In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes t ...

, 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 OMSI pb810, and a pair of paratypes which are currently preserved in the

paleobotanical 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 ...

collections of the Oregon Museum of Science and Industry in

Portland, Oregon Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous co ...

. The fossils were part of a group of approximately 20,000 specimens collected from 1942 to 1989 by Thomas Bones, A. W. Hancock, R. A. Scott, Steven R. Manchester, and a number of high school students. The ''Paleopanax'' specimens were studied by paleobotanist Steven R. Manchester of the University of Florida. He published his 1994

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 ''A. oregonensis'' in the Journal ''

Palaeontographica Americana The Paleontological Research Institution, or PRI, is a paleontological organization in Ithaca, New York, with a mission including both research and education. PRI is affiliated with Cornell University, houses one of the largest fossil collecti ...

''. In his type description Manchester noted the generic name is derived from the Greek word ''Paleo'' meaning "old" and '' Panax'' meaning "ginseng" in reference to the ginseng family. 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 ...

''oregonensis'' was chosen in recognition of the state of Oregon where the fossils were found. ''Paleopanax'' and fossil leaves of the genus '' Dendropanax'', from the Eocene of Tennessee, are considered the two oldest reliable records of Araliaceae.

Description

The fruits of ''Paleopanax oregonensis'' are bilaterally symmetrical with a wide elliptical shape in face view and bicarpellate structure. The fruits have an overall length ranging between and a width between . Each carpel is D-shaped in face view, with two to three arched longitudinal grooves which run across the carpel face and join at the ventral axis. The preserved

pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

are no more than long. The apex of the fruit sports two recurved styles which arise parallel to each other and are between long. Overall the fruit structure is very similar to those of the living ''

Pseudopanax davidii ''Pseudopanax'' (Latin for "false ginseng") is a small genus of 12–20 species of evergreen plants, the majority of which are endemic to New Zealand. Flowers of the genus occur in terminal umbels. Taxonomy A 2000 molecular study established t ...

''. The two species are distinguished by the style structure, with ''Pseudopanax davidii'' having a single forked style, while ''Paleopanax oregonensis'' has two separate styles.

References

{{Taxonbar, from=Q16756761 Araliaceae Monotypic Apiales genera Prehistoric angiosperm genera Fossil taxa described in 1994 Eocene plants Extinct flora of North America Flora of Oregon Prehistoric plants of North America Clarno Formation