27 Nisan 2013 Cumartesi

State Fossil of Virginia

State Fossil of Virginia

Marine Scallop (common name)
Chesapecten jeffersonius
(scientific name)
Chesapecten jeffersonius is the fossil of an extinct species of bivalve. A bivalve is a mollusk that has two symmetrical shells, such as modern oysters, clams, scallops, and mussels. Chesapecten jeffersonius was a marine scallop that inhabited the shallow waters of the coastal plain of Virginia approximately four to five million years ago in the early Pliocene epoch.
Throughout the Cenozoic era, the sea level bordering present-day eastern North America varied greatly. A wide variety and great abundance of fossils have been preserved in the rock of Virginia’s Coastal Plain. In addition to Chesapecten jeffersonius, numerous fossil clams and snails can be found in the rocks of southeast Virginia, as well as fossilized shark teeth and whalebones. Bivalves have also been fossilized in the rock of the Appalachian Mountains. Virginia designated Chesapecten jeffersonius its official state fossil in 1993.
This fossil was described and named by American naturalist and malacologist Thomas Say (1787–1834) in 1824. The genus name commemorates the location these specimens are found, the Chesapeake Bay, and the species name was chosen to honor Virginian Thomas Jefferson, who had an interest in natural history.
Chesapecten jeffersonius lived in an environment similar to that of modern scallops. These prehistoric bivalve mollusks inhabited the sand or mud of shallow seas. Also like modern scallops, these fossil species had deeply ridged shells, which the organism could clap together to propel itself through the water. Adults of the species swam freely after spending their youth attached to the seafloor. Most scallops eat plankton by filtration.
Chesapecten jeffersonius was among the most abundant scallops of its time. It became extinct about four million years ago in the early Pliocene epoch. The reason is not known for certain, but a possibility may be the cooling ocean temperatures that preceded the Pleistocene ice age.
Chesapecten jeffersonius was the first North American fossil ever to be described. English naturalist and physician Martin Lister (1638–1712) published a drawing of this fossil species in his famous publication Historiae Conchyliorum. This publication was completed over several years, between 1685 and 1692, and contains drawings made by Lister’s daughters. However, the fossil was not named until almost a century and a half later.
Geologist John Finch gave a large collection of fossil mollusks from Virginia, including Chesapecten jeffersonius, to the Academy of Natural Sciences of Philadelphia, the oldest natural science research institution and museum in the New World. This collection became North America’s first comprehensive collection of fossils.
Today, Chesapecten jeffersonius fossils are found along the Atlantic Coast and are most common in the Chesapeake Bay region. Several other species belonging to the genus Chesapecten can be found along the Eastern seaboard from New Jersey to Florida.
  • Thomas Say, who named Chesapecten jeffersonius, started his professional career as an apothecary. However, this self-taught naturalist changed careers, and in 1812 became a charter member and founder of the Academy of Natural Sciences of Philadelphia. He is known as the "father of descriptive entomology in the United States," having named almost 1,500 insects; several have since been named in his honor.
  • Native Americans once used Chesapecten jeffersonius as bowls and as tools for scooping and scraping.

Click to enlarge an image
State Prehistoric Creature
Live Scallop
State Prehistoric Creature
Front View of Fossilized Scallops
State Prehistoric Creature
Fossilized Scallops from the Back

Species:C. jeffersonius
Author: World Trade Press

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