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The Tremadocian is the lowest stage of Ordovician. Together with the later Floian Stage it forms the Lower Ordovician Epoch. The Tremadocian lasted from 485.4 to 477.7 million years ago. The base of the Tremadocian is defined as the first appearance of the conodont species Iapetognathus fluctivagus at the Global Boundary Stratotype Section and Point (GSSP) section on Newfoundland.
The Cambrian–Ordovician extinction event occurred approximately 488 million years ago (mya). This early Phanerozoic Eon extinction event eliminated many brachiopods and conodonts, and severely reduced the number of trilobite species. The Period in the Cambrian extinction in which most of the extinction occurred was the Caerfai Period.
The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from 497 to 485.4 million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three stages: the Paibian, Jiangshanian and the unnamed 10th stage of the Cambrian.
Thysanopyge is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived in what is now South America during the early part of the Arenig stage of the Ordovician Period, a faunal stage which lasted from approximately 478 to 471 million years ago.
Santa Rosita may refer to:
Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known member is Marrella, with thousands of specimens found in the Cambrian aged Burgess Shale of Canada. The group is divided up into two major orders, Marrellida and Acercostraca. Marrellida is recognised by the possession of head shields with two or three pairs of elongate spine-like projections, and three pairs of uniramous appendages on the cephalon, while Acercostraca generally have large ovoid carapaces that cover the entire upper half of the body, and five pairs of uniramous cephalic appendages. Both groups have unbranched antennules and a segmented trunk with biramous appendages. Recent research has suggested the previously enigmatic Cambrian trliobite-like arthropods Skania and Primicaris may belong to this group. Their phylogenetic position is uncertain, various studies have alternatively placed them within in the Arachnomorpha as relatives of Artiopoda, as stem-group Mandibulata, or as stem group euarthropods.
The Conococheague Formation is a mapped Appalachian bedrock unit of Cambrian age, consisting primarily of limestone and dolomite. It occurs in central Maryland, southern and central Pennsylvania, the Valley and Ridge of Virginia and easternmost West Virginia.
Megistaspis is a genus of trilobites in the order Asaphida and family Asaphidae.
Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite Lotagnostus americanus around 489.5 million years ago, but other fossils are also being discussed. The upper boundary is defined as the appearance of the conodont Iapetognathus fluctivagus which marks the beginning of the Tremadocian and is radiometrically dated as 485.4 million years ago.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2013.
Westergaardodina is a species-rich genus of spine, U or W-shaped paraconodont known from Middle Cambrian to Lower Ordovician strata.
Angelina Salter, 1859, is a genus of ptychopariid trilobite belonging to the Family Olenidae, Suborder olenina. It lived during the Tremadocian Stage, lowermost of the two standard worldwide divisions forming the Lower Ordovician Series and lowest of the seven stages within the Ordovician System. It encompasses all rocks formed during Tremadocian times, which spanned the interval between 485.4 million and 477.7 million years ago. Fossilized remains of Angelina are known from Wales, Central and South America. It differs from most other Triarthrinae in being larger, with a relatively narrow glabella, the occipital ring poorly defined, and lateral glabellar furrows relatively obscure. Eyes are placed midlength that of the cephalon and the facial sutures converge on the front border at the midline. Species also have long genal spines.
Granomarginata is a genus of spherical Cambrian acritarchs interpreted as a phytoplankton.
Acodus is an extinct genus of conodonts.
Acanthodus is an extinct genus of conodonts.
Kallidontus is an extinct genus of conodonts.
Variabiloconus is an extinct genus of conodonts.
Eoconodontus is an extinct genus of conodonts of the Late Cambrian. It is a two-elements genus from the Proconodontus lineage.
Conodonts are an extinct class of animals whose feeding apparatuses called teeth or elements are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils in the subfield of the stratigraphy named biostratigraphy.
Siphonotretida is an extinct order of linguliform brachiopods in the class Lingulata. The order is equivalent to the sole superfamily Siphonotretoidea, itself containing the sole family Siphonotretidae. They were most abundant in the Late Cambrian and Early Ordovician, and were traditionally considered to have gone extinct in the Upper Ordovician (Ashgill). However, they may have been present as early as Cambrian Stage 4, and as late as the Silurian (Ludlow). Siphonotretoids were originally placed as a superfamily of Acrotretida, before being raised to their own order.
References
- ↑ Miller, James F. (1980). "Taxonomic revisions of some Upper Cambrian and Lower Ordovician Conodonts with comments on their Evolution". The University of Kansas Paleontological Contributions. 99: 35–37. hdl: 1808/3732 . ISSN 0075-5052.
- ↑ Zeballo, Fernando J.; Albanesi, Guillermo L. (2013). "New conodont species and biostratigraphy of the Santa Rosita Formation (upper Furongian-Tremadocian) in the Tilcara Range, Cordillera Oriental of Jujuy, Argentina". Geological Journal. 48 (2–3): 181–187. doi:10.1002/gj.2425.
- ↑ Sepkoski, J. John Jr. (2002). Jablonski, David; Foote, Michael (eds.). "A Compendium of Fossil Marine Animal Genera". Bulletins of American Paleontology. 363: 548.
