''Dillhoffia'' 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 ...

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus of

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 ...

with a single species, ''Dillhoffia cachensis'' known from

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

age

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

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

British Columbia, Canada British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...

, and

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 on ...

, USA. The genus and species were described from fifteen specimens found in an unnamed formation belonging to the Kamloops group shales; and two specimens from the Klondike Mountain Formation. The unnamed formation outcrops at the

McAbee Fossil Beds The McAbee Fossil Beds is a Heritage Site that protects an Eocene Epoch fossil locality east of Cache Creek, British Columbia, Canada, just north of and visible from Provincial Highway 97 / the Trans-Canada Highway ( Highway 1). The McAbee Fos ...

near Cache Creek, BC, which is designated the type locality while the two U.S. specimens were recovered from the Tom Thumb Tuff member of the Klondike Mountain Formation in

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. It was the largest mining camp in the Republic Mining Distr ...

. It is of interest to note that of the Okanagan highlands fossil sites ''Dillhoffia'' is only known from two locations, and is absent or has not been identified from the others. 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, number ''TMP 83.39.175'', is preserved in the

Royal Tyrell Museum 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 situa ...

and the

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 are in the

Thompson Rivers University Thompson Rivers University (commonly referred to as TRU) is a public teaching and research university offering undergraduate and graduate degrees and vocational training. Its main campus is in Kamloops, British Columbia, Canada, and its name c ...

and

University of Saskatchewan A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, t ...

collections. The 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 ...

s Steven Manchester 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 Kathleen 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 ...

. Manchester and Pigg published the 2008

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 ''D. cachensis'' in the journal ''

Botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

'', Volume 86, number 9. They chose the generic name ''Dillhoffia'' to honor the brothers Richard M. Dillhoff and Thomas A. Dillhoff for their substantial contributions and promotion of Pacific Northwest North American

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

floras. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is a reference to Cache Creek, British Columbia, the nearest town to the McAbee site. ''Dillhoffia'' is known from

infructescence Infructescence (fruiting head) is defined as the ensemble of fruits derived from the ovaries of an inflorescence. It usually retains the size and structure of the inflorescence. In some cases, infructescences are similar in appearance to simple fru ...

s only. The infructescences are pedunculate having a globose head which bore at least twelve flowers and has been preserved as fossils with several sessile fruits. The fruits are elongate to ellipsoidal in form, being by , and

indehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...

. The enlarged calyx present on the fruits is thought to have been used for wind transport, with the calyx being dish to funnel shaped and born approximately three-quarters of the way up the fruit from the base. Formed from a persistent

perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepals when ...

, the calyx may have been accrescent, as small-sized calyces are known. It is unknown what the petals and stamens looked like, as none have been found, possibly being shed during fruit formation. ''Dillhoffia'' was most likely a non-magnoliid angiosperm as indicated by is inferior ovary, but placement into a specific family is not possible with the fossils known.

References

{{Taxonbar, from=Q20677408 Prehistoric angiosperm genera Monotypic angiosperm genera Enigmatic angiosperm taxa Fossil taxa described in 2008 Eocene plants Extinct flora of North America