Corylus johnsonii
Encyclopedia
Corylus johnsonii is an extinct species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of hazel known from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

s found in the Klondike Mountain Formation
Klondike Mountain Formation
The Klondike Mountain Formation is an early Eocene geologic formation that records the sedimentation in the southern most of a string of highland subtropical/Temperate lakes in Washington state and British Columbia. The formation is best known for exceptionally well preserved plant and insect fossils...

 deposits of Northern Washington State, dated to the early Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 Ypresian
Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....

 stage . Based on described features, C. johnsonii is the oldest definite species in the genus Corylus.

The description of the new species by Dr. Kathleen Pigg, Steven Manchester, and Wesley Wehr was based on the study of thirty-four compression fossil
Compression fossil
A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way...

 specimens found at the UWBM
Burke Museum of Natural History and Culture
The Burke Museum of Natural History and Culture has been a Washington state museum since 1899. It is located at the University of Washington campus at the intersection of N.E. 45th Street and 17th Avenue N.E. in Seattle, Washington, USA, in the University District. It is the only major natural...

 sites B4131 and A0307, the latter being designated the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....

. The specimens are twelve infructescence
Infructescence
Infructescence is defined as the ensemble of fruits derived from ovaries of an inflorescence, structured according to the inflorescence scheme....

s with attached involucres containing nuts
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...

 or nut casts, fourteen involucres, and eight isolated paired or single nuts. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 specimen is number "SR 98-01-02 A&B", an infructescence with involucre, and is housed in the Stonerose Interpretive Center
Stonerose Interpretive Center and Fossil Site
Established in 1989, the Stonerose Interpretive Center and Fossil Site is an Eocene Epoch fossil site and accompanying interpretive center, located in Republic, Washington, part of the Okanagan Highland. The fossils are from organisms that lived in the area nearly 50 million years ago when the area...

 in Republic, Washington
Republic, Washington
Republic is a city in Ferry County, Washington, United States. The population was 1,073 at the 2010 census, a 12.5% increase over the 2000 Census. It is the county seat of Ferry County.-History:...

. The species epithet johnsonii was coined in honor of Kirk R. Johnson for his continuing work on, and recognition of the importance of, the Republic Flora
Klondike Mountain Formation
The Klondike Mountain Formation is an early Eocene geologic formation that records the sedimentation in the southern most of a string of highland subtropical/Temperate lakes in Washington state and British Columbia. The formation is best known for exceptionally well preserved plant and insect fossils...

.

The infructescences bear between 2 and 3 nuts at the end of a stout stalk
Peduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...

. The nuts, 8 to 17 mm (0.31496062992126 to 0.669291338582677 in) in diameter, are ovoid
Oval
An oval is any curve resembling an egg or an ellipse, such as a Cassini oval. The term does not have a precise mathematical definition except in one area oval , but it may also refer to:* A sporting arena of oval shape** a cricket field...

 to almost circular in outline and enclosed in an involucre composed of 2 bracts
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...

. While most specimens consist of paired involucres with ovoid nuts or nut casts, several paired or isolated nuts are known. On the nuts themselves basal attachment scars cover a small area of nut; distal scars and style remains are preserved in several specimens. A predominant number of the fruits possess more dissected involucres, some having simple spines, while others have both simple and branched spines.

Though described as a single species, the authors noted the wide grade of variation in the involucre morphology, ranging from simple to ones with extensive spines. The involucres also show a spectrum from thin, leafy lobes that display distinct veins to thick lobes with no distinct venation. As specimens of C johnsonii have a full morphology range between the three involucre types, the possibility of multiple species is hard to prove or disprove. However the authors chose to name a single species because of the continuous gradation present between the distinct morphologies.

Of the two sections into which the genus Corylus is divided, section Corylus and section Acanthochlamys, C. johnsonii is most similar to three species in the latter. Section Acanthochlamys is considered basal within the genus and the three species, Corylus ferox, C.wangii, and C. heterophylla
Corylus heterophylla
Corylus heterophylla, the Asian Hazel, is a species of hazel native to eastern Asia, from northern China, eastern Mongolia, Korea, Japan, and southeastern Siberia....

are all native to southeast Asia. Infructescences of Corylus wangii, like those of C. johnsonii, possess narrow lobes with many unbranched and branched spines, while C. ferox-like infructescences have a highly spiny, prickly surface. Specimens within the simple end of the infructescence morphologic range are most similar to C. heterophylla. As C. johnsonii encompasses a wide morphology range within its features, it is possible it may have diverged out
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

 into the modern species. The modern areas of distribution for C.ferox and C. heterophylla overlap in the Sichuan province of China, while C. wangii has a distinct and separate range in southwest China.

Isolated nuts from Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

sediments in Greenland, England, and Montana have been attributed to the Corylus genus. However all lack the surrounding infructescence that is needed to confirm placement of the nuts in a specific coryloid genus.
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