'' 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 preserved ...

ized form of an extinct scallop, which lived in the early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million 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 by ...

between four and five million years ago on Virginia's

coastal plain A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf Co ...

. 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 The Yorktown Formation is a mapped bedrock unit in the Coastal Plain of Maryland, Virginia, North Carolina and South Carolina. It is overconsolidated and highly fossiliferous. Description The Yorktown is composed largely of overconsolidated san ...

. It is the state fossil of the

Commonwealth of Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...

in the United States.

Paleontological history

In 1687,

Martin Lister Martin Lister FRS (12 April 1639 – 2 February 1712) was an English naturalist and physician. His daughters Anne and Susanna were two of his illustrators and engravers. J. D. Woodley, ‘Lister , Susanna (bap. 1670, d. 1738)’, Oxford Dic ...

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 the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

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

Yorktown, Virginia Yorktown is a census-designated place (CDP) in York County, Virginia. It is the county seat of York County, one of the eight original shires formed in colonial Virginia in 1682. Yorktown's population was 195 as of the 2010 census, while York Co ...

, and gave them to scientists at the

Academy of Natural Sciences of Philadelphia The Academy of Natural Sciences of Drexel University, formerly the Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the Americas. It was founded in 1812, by many of the leading nat ...

(ANSP). Scientist

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

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

Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Father who served as the third president of the United States from 1801 to 1809. He was previously the natio ...

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 {{paleo-bivalve-stub