25 Mart 2013 Pazartesi

Missouri State Fossil

Missouri State Fossil

Sea Lily (common name)
Delocrinus missouriensis 
(scientific name)
Sea lilies, a type of crinoid, are marine animals that resemble plants. They belong to the class Crinoidea of the phylum Echinodermata. Echinoderms, which include modern sea urchins and starfish, are characterized by their radial symmetry and external skeletons. Delocrinus missouriensis is an extinct crinoid that displayed pentagonal symmetry. Its skeleton was made of small bony structures that didn’t normally remain together, making complete fossils of this species rare.
This sea lily lived approximately 250 to 300 million years ago in the Pennsylvanian period of the Paleozoic era. Delocrinus missouriensiswere common in the shallow seas that covered much of what is now western North America. Approximately 5,000 fossil species are known.
Today, crinoid bones called ossicles are commonly found as fossils in limestone deposits dating from the Paleozoic era, especially in the Burlington Formation of Missouri, Iowa, and Illinois, and in the Callaway Formation in central Missouri. Fossilized crinoid, scientifically designated as Delocrinus missouriensis, was declared the official fossil of the state of Missouri on June 16, 1989. The proposal came from a group of school students from Pleasant Lea Junior High School in Lee’s Summit, Missouri. The students proposed the fossil, promoted it, and worked through the legislative process to see their idea become reality.
This crinoid is called a sea lily because of its plant-like appearance. The word "crinoid" comes from the Greek κρίνος (krinos), which means "lily."
Crinoids are composed of three main body parts: the stem, the calyx, and the arms. The flexible stem usually anchored the organism to the bottom of the sea. Most of the sea lily’s body is made of calcium carbonate. Delocrinus missouriensis were stationary animals. They had five feather-like arms with which they filtered food particles into their mouths from the waters flowing past them. The main portion of the body may have reached up to 82 feet (25 m) in length.
Delocrinus missouriensis is related to modern sea urchins, sea cucumbers, and sand dollars. Although not nearly as common today as they were in Paleozoic times, some 80 species of sea lilies still live in deep and shallow seas. Today, they are not well known because they live in deep waters where little light and oxygen, and therefore little sea life, exists.
Sea lilies were extremely abundant in prehistoric seas until the Permo-Triassic extinction event, when they nearly became extinct. This mass extinction took place approximately 251 million years ago, wiping out nearly 96 percent of all marine species and 70 percent of all terrestrial vertebrates living at the time.
Fossilized fragments of crinoids, or sea lilies, have been found near the top of Mount Everest. This is considered evidence of the dynamic forces that drive faults.
In July 2009, a new species, and possibly also a new genus, of stalked crinoid was discovered in the western Atlantic Ocean. This crinoid belongs to a family previously unknown in that part of the world.

Click to enlarge an image
State Prehistoric Creature
Modern-day Sea Lily (Crinoid)
State Prehistoric Creature
Fossilized Sea Lilies
State Prehistoric Creature
Crinoid Ossicles
State Prehistoric Creature
Fossilized Sea Lily Roots

Order:(incertae sedis)
Species:D. missouriensis
Author: World Trade Press

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