|
Collier Shale
The Collier Shale is a geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. Dating from the Late Cambrian to Early Ordovician periods, the Collier Shale is the oldest stratigraphic unit exposed in Arkansas. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the type locality to the headwaters of Collier Creek in Montgomery County, Arkansas, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. Paleofauna Conodonts * ''Acanthodus'' : ''A. lineatus'' * ''Acodus'' : ''A. oneotensis'' * '' Chosonodina'' : ''C. herfurthi'' * '' Cordylodus'' : ''C. angulatus'' * '' Drepanodus'' : ''D. subarcuatus'' * '' Loxodus'' : ''L. bransoni'' * '' Oistodus'' : ''O. triangularis'' * '' Paltodus'' : ''P. bassleri'' * '' Phakelodus'' : ''P. tenuis'' Trilobites * '' Anechocephalus'' : ''A. aphelodermus'' * '' Apachia'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acodus
''Acodus'' is an extinct genus of conodonts. Species * ''A. acutus'' * ''A. campanula'' * ''A. crassus'' * ''A. delicatus'' * ''A. deltatus'' * ''A. erectus'' * ''A. firmus'' * ''A. jonesi'' * ''A. kechikaensis'' * ''A. neodeltatus'' * ''A. oneotensis'' * ''A. planus'' * ''A. primitivus'' * ''A. sigmoideus'' * ''A. similaris'' * ''A. tripterolobus'' * ''A. zeballus'' Distribution Fossils of ''Acodus'' have been found in Argentina, Canada (Ontario, Quebec, British Columbia, Northwest Territories, Nunavut), China, Colombia (Tarqui, Huila),Moreno et al., 2008, p.10 the Czech Republic, Estonia, Iran, Kazakhstan, Malaysia, the Russian Federation, Spain, Sweden, Thailand, the United Kingdom, and the United States (Indiana, New York, Tennessee, Nevada, Kentucky, Missouri, Ohio, Utah).''Acodus'' at |
Trilobita
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites 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 () 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. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. The stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Trilobita")