Delaware State Fossil
Belemnite (common name) Belemnitella americana (scientific name) STATUS Official  DESCRIPTION A belemnite is a member of an extinct group of marine mollusks. Similar to the modern squid, octopus, and cuttlefish, the belemnites had an ink sac for defense purposes. Unlike their modern relatives, however, belemnites had 10 arms of equal length. Belemnites lived during the Cretaceous and Jurassic periods of the Mesozoic era, approximately 65 to 200 million years ago. Their fossils are found in rocks of this period, along with the fossils of other extinct cephalopods. A STATE SYMBOL Belemnitella americana fossils are commonly found in the Mount Laurel Formation along the shores of the Chesapeake and Delaware Canal, near St. Georges, Delaware. This species is found only in Delaware and the surrounding states. Based on a proposal from a third-grade class at the Martin Luther King, Jr. Elementary School in Wilmington, Belemnitella americana was designated the official fossil of the state of Delaware on July 2, 1996. NAME ORIGIN The name for this fossil comes from the Greek βέλος (belos), meaning "dart" or "arrow." BIOLOGY/ANATOMY Belemnites are cephalopods, the name coming from Greek and  meaning "head-foot." The subclass Coleoidea contains the soft-bodied cephalopods, which include squid and octopus. The belemnite’s slender, streamlined body, similar in size and shape to the modern squid's, made it a relatively fast swimmer. Instead of suckers like its modern relatives, belemnite’s arms were equipped with 30 to 50 slightly curved hooks to grab prey. Belemnite’s diet consisted of small fish and other marine animals. Plesiosaurs and ichthyosaurs, large marine reptiles that hunted in Mesozoic seas, fed on belemnites. This cephalopod had a conical, internal shell called a rostrum,  divided into chambers. This shell was covered with soft, leathery skin. Because it was strong and solid, the belemnite’s rostrum is the part that most easily fossilizes, and therefore is the most commonly found today. The fossils are mainly found in basal quartz sand, often with another relative of belemnites, the ammonites. EVOLUTION/EXTINCTION Belemnites became extinct at about the same time dinosaurs did, approximately 65 million years ago at the end of the Cretaceous period. It is not known for certain what caused this mass extinction, known as the Cretaceous–Tertiary or Cretaceous–Paleogene extinction event. However, scientists consider rapid climate change brought on by an asteroid impact to be a strong possibility; disease and gradual climate change are other theories. Change in marine population, including belemnite’s predators and prey, may also be a cause. MODERN DISCOVERY Belemnitella americana fossils were first discovered in the Chesapeake and Delaware Canal area during the canal’s construction in the 1820s. Specimens can still be found in this part of Delaware today. Fossils of other species of belemnites are found along the eastern seaboard of the United States, in the western United States (especially in present-day Utah), and in parts of Europe, specifically Germany and the United Kingdom. TRIVIA Today, geologists, paleontologists, and other scientists report oxygen isotope and carbon isotope ratios relative to a standard called the PDB (Pee Dee Belemnite) or the equivalent VPDB (Vienna PDB). The ratios can be used as indicators of various factors in paleoclimatology, paleoceanography, and geochemistry. The original PDB sample was a sample of fossilized shells of extinct belemnites, collected decades ago from the banks of the Pee Dee River in South Carolina.
	Click to enlarge an image Belemnite, a Squid Relative  Collection of Belemnite Fossils Belemnite Fossil CLASSIFICATION Kingdom: Animalia Phylum: Mollusca Class: Cephalopoda Subclass: Coleoidea Unranked: Belemnoidea (nomen nudum) Belemnitella    americana
	Author: World Trade Press