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Planohybodus
''Planohybodus'' (from Latin ''planus'', "flat", and "''Hybodus''") is an extinct genus of hybodont, known from the Middle Jurassic-Early Cretaceous (Bathonian-Barremian) of Europe (including Great Britain, France, Spain, Switzerland, Poland, and possibly Denmark) and the Indian subcontinent. Fossils have been found in marine as well as freshwater environments. The genus contains 3 confirmed species, two of which were originally assigned to the genus ''Hybodus.'' Possible records have been reported from the Late Jurassic of Mexico, the Early Cretaceous of Brazil (''Planohybodus marki'') and the Late Cretaceous (Santonian) of North America, but these are unconfirmed. ''Planohybodus peterboroughensis'' is suggested to have reached lengths of . A specimen of the ammonite genus '' Orthaspidoceras'' from the Late Jurassic of France has been found with an embedded tooth of ''Planohybodus'', suggesting that while the teeth of ''Planohybodus'' were adapted to tearing soft bodied prey, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodontiformes
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays (Neoselachii) as part of the clade Euselachii. They are distinguished from other chondrichthyans by their distinctive fin spines and cephalic spines present on the heads of males. An ecologically diverse group, they were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct. Etymology The term hybodont comes from the Greek word ''ὕβος'' or ''ὑβός'' meaning hump or hump-backed and ''ὀδούς, ὀδοντ'' meaning tooth. This name was g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodus
''Hybodus'' (from , 'crooked' and 'tooth') is an extinct genus of Hybodontiformes, hybodont. Species closely related to the type species ''Hybodus reticulatus'' lived during the Early Jurassic epoch. Numerous species have been assigned to ''Hybodus'' spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination. Description ''Hybodus'' species typically grew to about in length, with larger specimens of ''H. hauffianus'' reaching about . It possessed a streamlined body shape similar to modern sharks, with two similarly sized dorsal fins. As in other Hybodontiformes, dentinous fin spines were present on the dorsal fins of ''Hybodus,'' which in this genus exhibit a rib-like ornamentation located towards the tip of the spine, with rows of hooked Denticle (tooth feature), denticles present on the posterior side. The males possessed claspers, specialized organs that directly insert sperm into the female, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathonian
In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Stratigraphic definitions The Bathonian Stage takes its name from Bath, Somerset, Bath, a spa town in England built on Jurassic limestone (the Latinized form of the town name is ''Bathonium''). The name was introduced in scientific literature by Belgian geologist Jean Baptiste Julien d'Omalius d'Halloy, d'Omalius d'Halloy in 1843. The original type locality (geology), type locality was located near Bath. The French palaeontologist Alcide d'Orbigny was in 1852 the first to define the exact length of the stage. The base of the Bathonian is at the first appearance of ammonite species ''Parkinsonia (ammonite), Parkinsonia (Gonolkites) convergens'' in the stratigraphic column. The global referen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites '' Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradesh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Subcontinent
The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian Ocean between the Bay of Bengal to the east and the Arabian Sea to the west. It is now divided between Bangladesh, India, and Pakistan. (subscription required) Although the terms "Indian subcontinent" and "South Asia" are often also used interchangeably to denote a wider region which includes, in addition, Bhutan, the Maldives, Nepal and Sri Lanka, the "Indian subcontinent" is more of a geophysical term, whereas "South Asia" is more geopolitical. "South Asia" frequently also includes Afghanistan, which is not considered part of the subcontinent even in extended usage.Jim Norwine & Alfonso González, ''The Third World: states of mind and being'', pages 209, Taylor & Francis, 1988, Quote: ""The term "South Asia" also signifies the Indian Subcontinent""Raj S. Bhopal, ''Ethnicity, race, and health in multicultural societies'', pages 33, Oxford University Press, 2007, ; Q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.Gradstein ''et al.'' (2004) Stratigraphic definition The Santonian Stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, where the original type locality is located. The base of the Santonian Stage is defined by the appearance of the inoceramid bivalve ''Cladoceramus undulatoplicatus''. The GSSP (official reference profile) for the base of the Santonian Stage is located near Olazagutia, Spain; it was ratified by the Subcommission on Cretaceous Stratigraphy in 2012. The Santonian's top (the base of the Campanian Stage) is informally marked by the extinction of the crinoid '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthaspidoceras
''Orthaspidoceras'' is an extinct ammonoid cephalopod genus belonging to the family Aspidoceratidae. These nektonic carnivores lived during the Jurassic period, Kimmeridgian age.Sepkoski, JacSepkoski's Online Genus Database – Cephalopoda Description Shells of ''Orthaspidoceras'' are medium or large-sized, with a diameter reaching about . These shells are relatively involute and thick, with a quadrate-rounded or depressed whorls. The ornamentation consists of a row of coarse tubercles and fine streaks. Distribution Jurassic deposites of Italy, Mexico, Switzerland and Yemen.Paleobiology Database – Orthaspidoceras 2014-05-29. References * Arkell, et al.,1957. Mesozoic Ammonoidea; |
Callovian
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 165.3 ± 1.1 Ma (million years ago) and 161.5 ± 1.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian. Stratigraphic definitions The Callovian Stage was first described by French palaeontologist Alcide d'Orbigny in 1852. Its name derives from the latinized name for Kellaways Bridge, a small hamlet 3 km north-east of Chippenham, Wiltshire, England. The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus '' Kepplerites'' first appears, which is the base of the biozone of '' Macrocephalites herveyi''. A global reference profile (a GSSP) for the base had in 2009 not yet been assigned. The top of the Callovian (the base of the Oxfordian) is at the first appearance of ammonite species '' Brightia thuouxensis''. Subdivision The Callovian is often subdivided into three substages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxfordian (stage)
The Oxfordian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the earliest age (geology), age of the Late Jurassic epoch (geology), Epoch, or the lowest stage (stratigraphy), stage of the Upper Jurassic series (stratigraphy), Series. It spans the time between 161.5 ± 1.0 Annum#SI prefix multipliers, Ma and 154.8 ± 0.8 Ma (million years ago). The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian. Stratigraphic definitions The Oxfordian Stage was called "Clunch Clay and Shale" by William Smith (1815–1816); in 1818 W. Buckland described them under the unwieldy title "Oxford, Forest or Fen Clay". The term Oxfordian was introduced by Alcide d'Orbigny in 1844. The name is derived from the English city of Oxford, where the beds are well developed, but they crop out almost continuously from Dorset to the coast of Yorkshire, generally forming low, broad valleys. They are well exposed at Weymouth, Dorset, Weymouth, Oxford, Bedfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berriasian
In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 143.1 ±0.6 Ma and 137.05 ± 0.2 (million years ago). The Berriasian succeeds the Tithonian (part of the Jurassic) and precedes the Valanginian. Stratigraphic definition The Berriasian Stage was introduced in scientific literature by Henri Coquand in 1869. It is named after the village of Berrias in the Ardèche department of France. The largely non-marine English Purbeck Formation is in part of Berriasian age. The first rocks to be described of this age were the beds of the English Purbeck Formation, named as the Purbeckian by Alexandre Brongniart in 1829 following description by Henry De la Beche, William Buckland, Thomas Webster and William Henry Fitton. The base of the Berriasian, which is also the base of the Cretaceous System, has traditionally been placed at the first appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 2008
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, seashell, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in #Resin, 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 bef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
