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Lethenia
''Lethenia'' is an extinct genus of mackerel shark from the Rupelian age of the Oligocene epoch. It is a monotypic genus, containing only ''L. vandenbroeki''. It is considered closely related to ''Isurolamna'' and sometimes included within it. It differs in the morphology of its teeth, which are much more gracile than ''Isurolamna'' and has larger spacing between its crown and lateral cusps. ''Lethenia'' is rare and only known from isolated teeth. It is best known from the Boom Clay Formation of Belgium and the Uzunbas Formation of Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th .... References Prehistoric shark genera Fossil taxa described in 1999 Lamnidae Monotypic prehistoric cartilaginous fish genera {{Paleo-shark-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamnidae
The Lamnidae are the family of mackerel sharks known as white sharks. They are large, fast-swimming predatory fish found in oceans worldwide, though they prefer environments with colder water. The name of the family is formed from the Greek word ''lamna'', which means "fish of prey", and was derived from the Greek legendary creature, the Lamia.: ''A source-book of biological names and terms'', 1944, Edmund Carroll Jaeger These sharks have pointed snouts, spindle-shaped bodies, and large gill openings. The first dorsal fin is large, high, stiff and angular or somewhat rounded. The second dorsal and anal fins are minute. The caudal peduncle has a couple of less distinct keels. The teeth are gigantic. The fifth gill opening is in front of the pectoral fin and spiracles are sometimes absent. They are powerful, heavily built sharks, sometimes weighing nearly twice as much as other sharks of comparable length from other families. Many sharks in the family are among the fastest-swim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isurolamna
''Isurolamna'' is an extinct genus of Lamnidae, mackerel shark from the Paleogene, Paleogene period. It contains at least three species and a fourth is sometimes placed in it. It is thought to be closely related to ''Macrorhizodus'', ''Isurus'', and ''Cosmopolitodus''. ''Isurolamna'' arose in the Paleocene epoch during the Selandian age, and was extinct by the close of the Rupelian age of the Oligocene epoch. Some features which define this genus include a small, elliptical foramen (hole) in the middle of the lingual side of the root, triangular cusps except on lower interior teeth, and a relatively thick root with nearly vertical margins. The genus has a complicated taxonomic past. Species The following species are ascribed to the genus: References {{Taxonbar, from=Q104853156 Lamnidae Prehistoric shark genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rupelian
The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian Stage. Name The stage is named after the small river Rupel in Belgium, a tributary to the Scheldt. The Belgian Rupel Group derives its name from the same source. The name Rupelian was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1850. The separation between the group (stratigraphy), group and the stage was made in the second half of the 20th century, when stratigraphers saw the need to distinguish between lithostratigraphy, lithostratigraphic and chronostratigraphy, chronostratigraphic names. Stratigraphic definition The base of the Rupelian Stage (which is also the base of the Oligocene Series) is at the extinction of the foram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene Epoch
The Oligocene ( ) is a geologic epoch of the Paleogene Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from Ancient Greek (''olígos'') 'few' and (''kainós'') 'new', and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion of gras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic Taxon
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of Genus, genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belgium
Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to the south, and the North Sea to the west. Belgium covers an area of and has a population of more than 11.8 million; its population density of ranks List of countries and dependencies by population density, 22nd in the world and Area and population of European countries, sixth in Europe. The capital and Metropolitan areas in Belgium, largest metropolitan region is City of Brussels, Brussels; other major cities are Antwerp, Ghent, Charleroi, Liège, Bruges, Namur, and Leuven. Belgium is a parliamentary system, parliamentary constitutional monarchy with a complex Federation, federal system structured on regional and linguistic grounds. The country is divided into three highly autonomous Communities, regions and language areas o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to the China–Kazakhstan border, east, Kyrgyzstan to the Kazakhstan–Kyrgyzstan border, southeast, Uzbekistan to the Kazakhstan–Uzbekistan border, south, and Turkmenistan to the Kazakhstan–Turkmenistan border, southwest, with a coastline along the Caspian Sea. Its capital is Astana, while the largest city and leading cultural and commercial hub is Almaty. Kazakhstan is the world's List of countries and dependencies by area, ninth-largest country by land area and the largest landlocked country. Steppe, Hilly plateaus and plains account for nearly half its vast territory, with Upland and lowland, lowlands composing another third; its southern and eastern frontiers are composed of low mountainous regions. Kazakhstan has a population of 20 mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Shark Genera
Prehistory, also called pre-literary history, is the period of human history Human history or world history is the record of humankind from prehistory to the present. Early modern human, Modern humans evolved in Africa around 300,000 years ago and initially lived as hunter-gatherers. They Early expansions of hominin ... between the first known use of stone tools by hominins 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 years ago. It took thousands of years for writing systems to be widely adopted, with writing having spread to almost all cultures by the 19th century. The end of prehistory therefore came at different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. It is based on an old conception of history that without ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 1999
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of ''Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before print. The ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
