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Cyrtonybyoceras
''Cyrtonybyoceras'' is a genus of slightly exogastric members of the Wutinoceratidae, a family of actinocerids and probably derived from an earlier ''Wutinoceras'' . The shell of ''Cyrtonybyoceras'' is curved slightly upwardly and is slightly compressed. Sutures slope toward the aperture, from the dorsum to the venter. The siphuncle is ventral but not marginal, in general form like that of ''Nybyoceras''. Upper and lower septal necks are recumbent or narrowly free. The canal system is reticular, characteristic of the Wutinoceratidae.Flower R.H.,1968;The First Great Expansion of the Actinoceroids, New Mexico Bureau of Mines and Mineral Resources, Memoir 19 Part I, Socorro NM ''Cyrtonybyoceras'' and ''Wutinoceras'' are similar, except for ''Cyrtonybyoceras'' being slightly cyrtoconic, and almost intergrade. ''Cyrtonybyoceras'' is so far known only from the Whiterock Stage in North America. The genotype, ''Cyrtonybyoceras haesitans'', was named by Teichert in 1933, based on ''Orthoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wutinoceratidae
The Wutinoceratidae are a family of early actinocerids defined by Shimazu and Obata in 1938Flower 1976. New American Wutinoceratidae with Review of Actinoceroid Occurrences in Eastern Hemisphere;PartI, Memoir 28; New Mexico Bureau of Mines and Mineral Resources for actinocerids with thick connecting rings and a complex irregular canal system. Actinocerids are generally straight shelled nautiloid cephalopods with a siphuncle composed of expanded segments, typically with thin connecting rings, in which the internal deposits are penetrated by a system of canals.Teichert 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, part K.(Nautiloidea) The Wutinoceratidae include three genera,Flower 1957. Studies of the Actinoceratida. Memoir 2; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM ''Wutinoceras'', ''Cyrtonybyoceras'', and ''Adamsoceras'', known especially from the early Middle Ordovician (Whiterock stage) in northeastern China and North America, but foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinocerida
The Actinocerida are an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial canals and a narrow space along the inner side of the connecting ring known as a paraspatium. (Teichert 1964) Septal necks are generally short and cyrtochoanitic, some being recumbent, some hook shaped. Most grew to lengths of about but some, like the Huroniidae of the Silurian grew significantly larger. Ecology The Actinocerida inhabited shallow to quite deep waters, where they alternated between swimming and lying on the bottom. They were predatory, and able to control their buoyancy to a greater degree than their contemporaries. Derivation The derivation of the Actinocerida remains enigmatic. They first appear late in the Early Ordovician (Cassinian Stage, late Floian) with the Georginida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wutinoceras
''Wutinoceras'' is a genus of now extinct nautiloid cephalopods of the Wutinoceratidae family. It exhibits orthoconic actinocerids with ventral siphuncles composed of broadly expanded segments.Memoir 2, Studies of the Actinocerida, New Mexico Bureau of Mines and Mineral ResourcesMemoir 19, The First Great Expansion of the Actinoceroids, New Mexico Bureau of Mines and Mineral Resources Distinguishing characteristics ''Wutinoceras'', as with its family the Wutinoceratidae, has a reticulated canal system within the siphuncle, distinguishing it from later forms with arcuate canal systems. Septal necks, components of the siphuncle that project from the back side of the septa, are cyrtochoanitic (outwardly curved) and may be recumbent. Connecting rings are thick, reflective of the ancestral form. Varieties The three varieties of ''Wutinoceras'' are based on the form of the siphuncle, and each contains a number of species. These have not been ascribed to subgenera. They include th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nybyoceras
''Nybyoceras'' is an actinocerid genus assigned to the Armenoceratidae and similar to ''Armenoceras'' except for having a siphuncle close to the ventral side of the shell. Morphology As with ''Armenoceras'', ''Nybyoceras'' has a medium to large, straight shell.(Teichert 1964) Its primary diagnostic feature is its ventral siphuncle which the septa across obliquely.(Flower 1957,Teichert 1964) Ventrally, the septal necks are short and free, or recumbent for a short distance. Dorsally the brims are definitely recumbent.(Flower 1957) The connecting rings are broadly adnate to the septa ventrally at the posterior ends of the segments and dorsally at the anterior (adoral) ends.(Teichert 1964) Flower (1957) described the canal system within the siphuncle as being primarily of the single arc type, like ''Armenoceras'', and with interconnecting tubes. Teichert (1964) describes the canal system as being reticulate to curved and branching. Phylogengy and distribution ''Nybyoceras'' is de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whiterock Stage
The Whiterockian, often referred to simply as the Whiterock, is an earliest or lowermost stage of the Middle Ordovician. Although the Whiterockian or Whiterock Stage refers mainly to the early Middle Ordovician in North America, it is often used in the older literature in a global sense. The Whitetrock Stage was introduced by Cooper and Cooper (in Cooper, 1956, p. 6–7) "as a post-Canadian – pre-Chazyan chrono-stratographic unit" based on strata "in the Monitor and Antelope Ranges, flanking Antelope Valley, and in the Toquima Range of central Nevada", referred to as the Antelope Valley Limestone. The strato-type section in Whiterock Canyon in the northern Monitor Range and reference section at Meiklejohn Peak, Bare Mountain Quad. Nev. both show the boundary between the middle Ordovician Whiterock and underlying (mostly Canadian) Ibex series lies between the conodont ''Oepikodus evae'', below, and ''Tripodus laevis'', above, at the start of the ''Isograptus victoria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antelope Valley (Eureka County)
The Antelope Valley of southern Eureka County is a small 35 mi (56 km) longNevada Atlas & Gazetteer, DeLorme, c. 2010, p. 46-47. valley, surrounded by four mountain ranges. Antelope Wash flows north, to endorheic flatlands at the valley's north end. Eureka, Nevada lies 20 mi east nestled among mountain ranges. From Eureka U.S. Route 50 travels west through the north end of the valley on a route to Austin. Description Antelope Valley is about long, north-south trending, and lies at the northeast foothills of the extensive north-south Monitor Range. The southeast portion is within the Toiyabe National Forest. Antelope Valley begins as Antelope Wash in northern Nye County between the Monitor Range and the Antelope Range. The headwaters of the valley begin as a narrow mountain valley on the north side of a water divide about south of the Nye-Eureka line. Antelope Valley broadens to about wide at about to the north. Thereafter Antelope Valley merges with the Monitor Vall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toquima Range
The Toquima Range is a mountain range, located primarily in Nye County with a small extension into Lander County, in Nevada, United States. Most of the range is included within the Humboldt-Toiyabe National Forest. The range reaches a maximum elevation of 11,949 feet (3,642 m) at the southern summit of Mount Jefferson. From Hickison Summit on U.S. Route 50, the range runs for approximately 71 miles (115 km) to the south-southwest. To its west are Big Smoky Valley, scenic State Route 376, and the large Toiyabe Range. To the east are remote Monitor Valley and the Monitor Range. Lying to the south of the range are U.S. Route 6 (Nevada) and the community of Tonopah, while to the north is U.S. Route 50 ("The Loneliest Highway in America"), leading to the small community of Austin. The high central section of the Toquima Range is a large area of subalpine tundra surrounding the three summits of Mount Jefferson. This section of the range is protected as the Alta T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Nautiloid Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic Life Of Newfoundland And Labrador
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ''zōḗ'' (), "life", meaning "ancient life" ). It is the longest of the Phanerozoic eras, lasting from , and is subdivided into six geologic periods (from oldest to youngest): # Cambrian # Ordovician # Silurian # Devonian # Carboniferous # Permian The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era. The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, reptiles, and synapsids all evolved during the Paleozoic. Life began in the ocean but even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
