'' Chesapecten jeffersonius '' is the

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 preserve ...

ized form of an extinct

scallop Scallop () is a common name that encompasses various species of marine bivalve molluscs in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related famili ...

, which lived in the early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

between four and five

million 1,000,000 (one million), or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian ''millione'' (''milione'' in modern Italian), from ''mille'', "thousand", plus the ...

years ago on Virginia's

coastal plain A coastal plain (also coastal plains, coastal lowland, coastal lowlands) is an area of flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and an upland area. Formation Coastal plains can f ...

. ''Chesapecten jeffersonius'' are commonly found in strata exposed along Coastal Plain cliffs along major rivers in southeastern Virginia and eastern North Carolina, and it is the index fossil for the Lower Yorktown Formation. It is the

state fossil Most states in the US have designated a state fossil, many during the 1980s. It is common to designate a fossilized species, rather than a single specimen or a category of fossils. State fossils are distinct from other state emblems like state d ...

of the

Commonwealth of Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

in the United States.

Paleontological history

In 1687,

Martin Lister Martin Lister (12 April 1639 – 2 February 1712) was an English natural history, naturalist and physician. His daughters Anne Lister (illustrator), Anne and Susanna Lister, Susanna were two of his illustrators and engravers. J. D. Woodley, 'L ...

published a drawing of ''C. jeffersonius'', making it the first North American fossil to be illustrated in scientific literature. In 1824, geologist John Finch gathered a large collection of

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

fossils, including ''Chesapecten jeffersonius'', from the vicinity of

Yorktown, Virginia Yorktown is a town in York County, Virginia, United States. It is the county seat of York County, one of the eight original shires formed in Colony of Virginia, colonial Virginia in 1682. Yorktown's population was 195 as of the 2010 census, while ...

, and gave them to scientists at the Academy of Natural Sciences of Philadelphia (ANSP). Scientist

Thomas Say Thomas Say (June 27, 1787 – October 10, 1834) was an American entomologist, conchologist, and Herpetology, herpetologist. His studies of insects and shells, numerous contributions to scientific journals, and scientific expeditions to Florida, Ge ...

, at ANSP, described the species and named it ''Pecten jeffersonius'' to honor

Thomas Jefferson Thomas Jefferson (, 1743July 4, 1826) was an American Founding Fathers of the United States, Founding Father and the third president of the United States from 1801 to 1809. He was the primary author of the United States Declaration of Indepe ...

Identification

''Chesapecten jeffersonius'' is distinguished from other ''Chesapecten'' species by the number of ribs (9 to 12), and a rather rounded shell edge.

References

Virginia: ''Chesapecten jeffersonius'' (state fossil)
Pectinidae Neogene bivalves Pliocene animals of North America Symbols of Virginia Taxa named by Thomas Say Prehistoric bivalves Bivalves described in 1824 {{Pectinidae-stub