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Gun River Formation
The Gun River Formation is a geologic formation in Quebec. It preserves fossils dating back to the early Silurian period. Description The formation is divided into 4 members (from the base up): the Lachute, Innommée, Sandtop and Macgilvray members. The formation was deposited some 40–80 km offshore from the stable Laurentian craton, underwater at depths of 30 to 60 meters. Fossil content Vertebrates Invertebrates See also * List of fossiliferous stratigraphic units in Quebec This is a list of fossiliferous stratigraphic units in Quebec, Canada. References * {{Lists of fossiliferous stratigraphic units in Canada Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accen ... References * Silurian Quebec Silurian southern paleotemperate deposits Silurian southern paleotropical deposits {{Quebec-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
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 (geology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strophomenida
Strophomenida is an extinct order of articulate brachiopods which lived from the lower Ordovician period to the mid Carboniferous period. Strophomenida is part of the extinct class Strophomenata, and was the largest known order of brachiopods, encompassing over 400 genera. Some of the largest and heaviest known brachiopod species belong to this class. Strophomenids were among the most diverse and abundant brachiopods during the Ordovician, but their diversity was strongly impacted at the Late Ordovician mass extinction. Survivors rediversified into new morphologies in the Silurian, only to be impacted once again at the Late Devonian mass extinction. However, they still survived till the mid Carboniferous. Adult strophomenids lack an opening for the pedicle (stalk), so in life, they either lay free or cemented the ventral valve (lower shell) onto a firm substrate at the umbo (hinge). In juveniles, a tiny hole for the pedicle was present on the ventral valve near the umbo, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentamerus
:''The gall mite genus ''Pentamerus'', established by Roivainen in 1951, is invalid and needs to be renamed. Until this happens, use '' Pentamerus (mite)''.'' ''Pentamerus'' (meaning "five thighs") is a prehistoric genus of brachiopods that lived from the Silurian to the Middle Devonian in Asia, Europe, and North America. See also * Pentamerus Range Sources * ''Fossils'' (Smithsonian Handbooks) by David Ward (Page 82) External links''Pentamerus''in the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Paleo ... Rhynchonellata Prehistoric brachiopod genera Silurian brachiopods Devonian brachiopods Paleozoic animals of Asia Prehistoric animals of Europe Paleozoic brachiopods of North America Silurian first appearances Middle Devonian genus extinctions F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meristina
''Meristina'' is an extinct genus of brachiopods that lived from the Late Ordovician to the Middle Devonian of Asia, Europe, and North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car .... ''Meristina'' had a smooth convex shell with a one-inch diameter. Sources * ''Fossils'' (Smithsonian Handbooks) by David Ward (Page 85) External links''Meristina''in the Paleobiology Database Spiriferida Prehistoric brachiopod genera Ordovician brachiopods Silurian brachiopods Devonian brachiopods Paleozoic animals of Asia Prehistoric animals of Europe Paleozoic brachiopods of North America Late Ordovician first appearances Middle Devonian genus extinctions Paleozoic life of Ontario Paleozoic life of British Columbia Paleozoic life of Manitoba Paleozoic life of New ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dalmanellidina
Orthida is an extinct order of brachiopods which appeared during the Early Cambrian period and became very diverse by the Ordovician, living in shallow-shelf seas. Orthids are the oldest member of the subphylum Rhynchonelliformea, and is the order from which all other brachiopods of this group stem. Physically they are usually strophic, with well-developed interareas. They also commonly have radiating ribs, sulcus, and fold structures. Typically one valve, often the brachial valve, is flatter than the other. The interior structure of the brachial valves are usually simple. In shape they are sub-circular to elliptical, with typically biconvex valves. There is some debate over the forms that first appeared of this order as to how they should be classified. However, they began to differentiate themselves by the late Early Cambrian period, and by the late Cambrian period had diversified into numerous varieties and reach 2 to 5 cm in width. Specimens from the late Cambria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentamerida
Pentamerida is an order of biconvex, impunctate shelled, articulate brachiopods that are found in marine sedimentary rocks that range from the Middle Cambrian through the Devonian.Moore, Lalcker and Fischer, 1952, Invertebrate Fossils, McGraw-Hill Pentamerids are characterized by a short hinge line where the two valves articulate, inner areas above the hinge line that slope inwardly from the beak of each valve, and a well-developed spondylium on the pedicle valve. The spondylium is a raised platform for muscle attachment found in the middle of the interior pedicle valve, generally toward the hinge and beak. The pedicle valve is the one that the pedicle, or hold-fast stalk, attaches to. The brachidia, which hold the lophophore, the ciliated feeding arms, are looped, as in the Orthida. The Short hinge line helps distinguish the pentamerids from the ancestral orthids from which they are obviously derived. The hinge line is not as short as found in the Rhynchonellida The taxon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athyridida
Athyridida is an order of Paleozoic brachiopods included in the Rhynchonellata, which makes up part of the articulate brachiopods. The Athyridida are the Rostrospracea of R.C Moore, 1952,Moore, Lalcker and Fischer, 1952, Invertebrate Fossils, McGraw-Hill considered at that time to be a suborder of the Spiriferida. As with the Spiriferida, the Athyridida have outwardly directed spiral brachidia that support the lophophores on either side, but instead have non-plicate shells with rounded outlines and prominent beaks but almost no inner areas on the pedicle valve. Athyridids began early in the Silurian, reached their greatest diversity in the following Devonian, and from then declined steadily until almost becoming extinct at the end of the Permian The order rejuvenated somewhat during the Triassic, only to decline again until becoming extinct in the Early Jurassic. ''Athyris'', '' Composita'', and ''Meristella ''Meristella'' is an extinct genus of brachiopods found from the Lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
