''Coryloides'' 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 ...

s in the

hazelnut The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus ''Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or filberts according t ...

family,

Betulaceae Betulaceae, the birch family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams, hazel-hornbeam, and hop-hornbeams numbering a total of 167 species. They are mostly natives of the t ...

, containing the single species ''Coryloides hancockii''. The species is solely known from the

middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

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 ...

nuts in

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 ...

History and classification

''Coryloides hancockii'' 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 Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer ...

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 UF 8497, which is 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

University of Florida The University of Florida (Florida or UF) is a public land-grant research university in Gainesville, Florida. It is a senior member of the State University System of Florida, traces its origins to 1853, and has operated continuously on its ...

and thirty-seven

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

specimens. Eight of the paratypes are also in the University of Florida collections, while twenty-five are in the

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...

collections, two are deposited at 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 ...

and the remaining specimen is part of the

University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...

, Museum of Paleontology. The fossils were part of a group of approximately 20,000 specimens collected from 1942 to 1989 by Thomas Bones, Alonzo W. Hancock, R. A. Scott, Steven R. Manchester, and a number of high school students. The ''Coryloides'' specimens 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 ...

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 ''C. hancockii'' 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 similarity of the fossils to the nuts of ''

Corylus The hazel (''Corylus'') is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,Germplasmgobills Information Network''Corylus''Rushforth, K. (1999). ...

''. 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 ...

''hancockii'' was chosen in honor of the amateur paleobotanist Alonzo W. Hancock, for his work establishing the field station next to the Clarno Nut Beds. Though originally informally identified as palm fruits, ''Coryloides'' is considered either to have been a sister genus of the hazelnuts in ''Corylus'', or as an example of parallel evolution in the subfamily

Coryloideae Coryloideae is a subfamily in the woody angiosperm family Betulaceae, commonly known as the birch family, and consists of four extant genera - ''Corylus'' L., ''Ostryopsis'' Decne., ''Carpinus'' L., and ''Ostrya'' Scop. These deciduous trees and ...

Description

The nuts of ''Coryloides hancockii'' are nearly perfectly spherical and rounded at both the apex and base. The nuts have an overall length ranging between and a diameter between . The nuts are

unilocular A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usu ...

in structure, containing a solitary nut. The nuts have an outer hull showing strong ribbing from base to apex and which are spaced about apart at the nut equator. The wall of the nut is thick and a large vascular bundle corresponds to each of the external ribs. The base is dominated by a circular basal scar in diameter and a stylar protrusion in diameter at the apex. The vascular bundles, unilocular nut and fruit, and circular detachment scar on the nut base are all features seen in the modern genus ''Corylus'', but the larger nut size and the nearly perfectly spherical nature of the nut are not seen in ''Corylus''.

References

{{Taxonbar, from=Q16752104 Betulaceae Prehistoric angiosperm genera Fossil taxa described in 1994 Eocene plants Flora of Oregon Monotypic Fagales genera Extinct flora of North America Prehistoric plants of North America Clarno Formation