Description: Trilobites, any member of a group of extinct fossil arthropods easily recognized by their distinctive three-lobed, three-segmented form. are extinct marine arthropods that form the class Trilobita, they form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period, 521 million years ago, and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described.By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Trilobites evolved into many ecological niches; some moved over the seabed as predators, scavengers, or filter feeders, and some swam, feeding on plankton. Some even crawled onto land. Most scientists believe that order Redlichiida, more specifically its suborder Redlichiina, contains a common ancestor of all other orders, with the possible exception of the Agnostina.The order Redlichiida is divided into two suborders: Olenellina and Redlichiina. The main difference between the two groups is the lack of facial sutures in the Olenellina. Fossils of olenellinid trilobites are found in North America, and other associated areas that comprised the Cambrian continent of Laurentia. They are very common and are used to define the extent of Laurentia. Their abrupt disappearance marks the boundary between the Lower and the Middle Cambrian.When trilobites are found, only the exoskeleton is preserved (often in an incomplete state) in all but a handful of locations. Trilobites in length with an average size range of 3–10 cm. Type Extinct marine arthropods Fossil rock RedlichiinaOrigin United StatesSize 5.6 cm (2'20 inches) Track Page Views WithAuctiva's Counter
Price: 23.89 AUD
Location: Strathpine, QLD
End Time: 2024-11-28T02:24:17.000Z
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Product Type: Fossils
Region: United States
Material: Fossil Rock
