''Cornus piggae'' is an extinct species of

dogwood ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous trees or shru ...

known from

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 found in

Late Paleocene The Thanetian is, in the ICS Geologic timescale, the latest age or uppermost stratigraphic stage of the Paleocene Epoch or Series. It spans the time between . The Thanetian is preceded by the Selandian Age and followed by the Ypresian Age (p ...

sediments exposed in the US state of

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, So ...

. ''C. piggae'' is one of three extinct species placed in the ''Cornus'' subgenus ''Cornus'' based on fossil fruit morphology. The other two species, '' C. ettingshausenii'' and '' C. multilocularis'' are known from pyritized fruits found in sediments of the

London Clay The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from t ...

in England. ''C. piggae'' is the only North American fruit species yet described and is also the oldest described species in ''Cornus'' subgenus ''Cornus''.

History and classification

''Cornus piggae'' is represented by a group of fifteen specimens from the

Tiffanian The Tiffanian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 60,200,000 to 56,800,000 years BP lasting . It is usually c ...

aged

Sentinel Butte Formation The Sentinel Butte Formation is a geologic formation of Paleocene age in the Williston Basin of western North Dakota. It preserves significant assemblages of non-marine plant and animal fossil A fossil (from Classical Latin , ) is any pr ...

which outcrops in near the town of

Almont, North Dakota Almont is a city in Morton County, North Dakota, United States. It is part of the " Bismarck, ND Metropolitan Statistical Area" or "Bismarck–Mandan". The population was 100 at the 2020 census. Almont was founded in 1906, incorporated in 1936, ...

and the Beicegal Creek, North Dakota. The age of the formation is based on the recovery of late Tiffanian mammals in the upper section of the formation along with the floral and

palynological Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and ''-logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposit ...

assemblages of the formation. Thirteen of the fossils were recovered from 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 ...

location 15722 at Almont while the remaining two are from location 18907 near Beicegal Creek. The

holotype specimen 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 ...

for ''Cornus piggae'' along with eight of 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). O ...

s are currently preserved in the paleobotanical collections of the Field Museum of Natural History in

Chicago, Illinois (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

. Five of the Almont paratype specimens and one Beicegal Creek specimen are in the university of Florida Collections, with the remaining Almont specimen housed at the

University of Wisconsin–Stevens Point The University of Wisconsin–Stevens Point (UW–Stevens Point or UWSP) is a public university in Stevens Point, Wisconsin. It is part of the University of Wisconsin System and grants associate, baccalaureate, and master's degrees, as well a ...

and the second Beicegal Creek specimen in the Arizona State University 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 ...

Steven R. Manchester of the university of Florida, and botanists Xiao-Ping Xiang of the

Chinese Academy of Sciences The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republi ...

, and Qiu-Yun (Jenny) Xiang of North Carolina State University. Manchester, Xiang, and Xiang published their 2010

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. piggae'' in the ''

International Journal of Plant Sciences The ''International Journal of Plant Sciences'' covers botanical research including genetics and genomics, developmental and cell biology, biochemistry and physiology, morphology and structure, systematics, plant-microbe interactions, paleobotany, ...

''. 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 ...

of the specific name ''piggae'' was derived from Professor Kathleen Pigg's name in honor of her contributions the field of paleobotany.

Description

Fossil specimens of ''Cornus piggae'' contain two to three locules and range from wide by in length. Both the apex and base are smooth with no apical depressions present and the smooth exterior of the fruits lacks ribbing. The apex hosts two to three germination valves which correspond to the elongate locules. The cell structure of the

endocarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...

indicates placement into ''Cornus'', while subglobose chambers in the walls of the locules are seen only in the ''Cornus'' subgenus ''Cornus''. The overall size of ''Cornus piggae'' is noted as distinctly smaller than the fruits of other living and extinct members in the subgenus.

References

{{Taxonbar, from=Q5171927 †Cornus piggae Flora of North Dakota Fossil taxa described in 2010 Plants described in 2010 Paleocene plants Extinct flora of North America