|
Didymoceras
''Didymoceras'' is an extinct genus of ammonite cephalopod from the Late Cretaceous epoch (approximately 76 Ma). It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down. The generic name is Greek for "paired horns". Its taxonomic place is often in flux, being placed in either Turrilitidae, Nostoceratidae Nostoceratidae is a diverse family of heteromorph ammonites found throughout the oceans of the world during the Late Cretaceous. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as '' Yezoceras'', '' Ain ..., or its own family, Didymoceratidae. Species included in the genus are the following: *''Didymoceras angulatum'' (Meek and Hayden, 1860) *''Didymoceras binodosum'' Kennedy and Cobban, 1993 *''Didymoceras californicum'' Anderson, 1958 *''Didymoceras cheyenense'' (Meek and Hayden, 1856) *''Didymoceras chey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didymoceras Stevensoni
''Didymoceras'' is an extinct genus of ammonite cephalopod from the Late Cretaceous epoch (approximately 76 Ma). It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down. The generic name is Greek for "paired horns". Its taxonomic place is often in flux, being placed in either Turrilitidae, Nostoceratidae Nostoceratidae is a diverse family of heteromorph ammonites found throughout the oceans of the world during the Late Cretaceous. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as '' Yezoceras'', '' Ain ..., or its own family, Didymoceratidae. Species included in the genus are the following: *''Didymoceras angulatum'' (Meek and Hayden, 1860) *''Didymoceras binodosum'' Kennedy and Cobban, 1993 *''Didymoceras californicum'' Anderson, 1958 *''Didymoceras cheyenense'' (Meek and Hayden, 1856) *''Didymoceras chey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didymoceras Cheyennese
''Didymoceras'' is an extinct genus of ammonite cephalopod from the Late Cretaceous epoch (approximately 76 Ma). It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down. The generic name is Greek for "paired horns". Its taxonomic place is often in flux, being placed in either Turrilitidae, Nostoceratidae Nostoceratidae is a diverse family of heteromorph ammonites found throughout the oceans of the world during the Late Cretaceous. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as '' Yezoceras'', '' Ain ..., or its own family, Didymoceratidae. Species included in the genus are the following: *''Didymoceras angulatum'' (Meek and Hayden, 1860) *''Didymoceras binodosum'' Kennedy and Cobban, 1993 *''Didymoceras californicum'' Anderson, 1958 *''Didymoceras cheyenense'' (Meek and Hayden, 1856) *''Didymoceras chey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didymoceras Nebrascensis
''Didymoceras nebrascense'' was an extinct species of heteromorph ammonite from the upper Campanian age (around 83 to 70 million years ago). It was sexually dimorphic, with two adult sizes averaging at and high for females and males respectively. It exhibited three distinct growth stages. The first growth stage was composed of one or two straight sharply bending sections and a gently curved third. The second growth stage is composed of around three and a half loosely coiling whorls. The last (adult) growth stage is composed of a U-shaped bend facing upwards. Description ''Didymoceras nebrascense'' is relatively easily identifiable. It has three growth stages. The initial growth stage produces two more or less straight sections connected with each other by a sharply bent elbow. The sections are parallel to each other or diverging at an angle of 10° to 30°. The second, larger straight section is elliptical in cross-section, higher than it is wide. It connects to a third more br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didymoceras Nebrascense
''Didymoceras nebrascense'' was an extinct species of heteromorph ammonite from the upper Campanian age (around 83 to 70 million years ago). It was sexually dimorphic, with two adult sizes averaging at and high for females and males respectively. It exhibited three distinct growth stages. The first growth stage was composed of one or two straight sharply bending sections and a gently curved third. The second growth stage is composed of around three and a half loosely coiling whorls. The last (adult) growth stage is composed of a U-shaped bend facing upwards. Description ''Didymoceras nebrascense'' is relatively easily identifiable. It has three growth stages. The initial growth stage produces two more or less straight sections connected with each other by a sharply bent elbow. The sections are parallel to each other or diverging at an angle of 10° to 30°. The second, larger straight section is elliptical in cross-section, higher than it is wide. It connects to a third more br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian spans the time from 83.6 (± 0.2) to 72.1 (± 0.2) million years ago. It is preceded by the Santonian and it is followed by the Maastrichtian. The Campanian was an age when a worldwide sea level rise covered many coastal areas. The morphology of some of these areas has been preserved: it is an unconformity beneath a cover of marine sedimentary rocks. Etymology The Campanian was introduced in scientific literature by Henri Coquand in 1857. It is named after the French village of Champagne in the department of Charente-Maritime. The original type locality was a series of outcrop near the village of Aubeterre-sur-Dronne in the same region. Definition The base of the Campanian Stage is defined as a place in the stratigraphic colu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonite
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) than they are to shelled nautiloids such as the living '' Nautilus'' species. The earliest ammonites appeared during the Devonian, with the last species vanishing during the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, and linking the rock layer in which a particular species or genus is found to specific geologic time periods is often possible. Their fossil shells usually take the form of planispirals, although some helically spiraled and nonspiraled forms (known as heteromorphs) have been found. The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder ( 79 AD ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nostoceratidae
Nostoceratidae is a diverse family of heteromorph ammonites found throughout the oceans of the world during the Late Cretaceous. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as '' Yezoceras'', '' Ainoceras'', '' Anaklinoceras'', and some species of ''Bostrychoceras'' and ''Eubostrychoceras'', display, as young shells at least, a helical coiling very similar to the shells of the related family, Turrilitidae. As adults, though, the coils then curve away from the axis of coiling, either as an oxbow-like curve around the juvenile coils as in ''Ainoceras'' and ''Anaklinoceras'', or in a simple curved loop beneath the juvenile coils, as in ''Yezoceras''. Other genera form loose coils, sometimes in a spiral, such as those of '' Madagascarites'', ''Muramotoceras'', '' Hyphantoceras'', and the infamously convolute ''Nipponites''. The ecology of nostoceratids is the subject of continued speculation, as the bizarrely coiled shells have no st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpheus Hyatt
Alpheus Hyatt (April 5, 1838 – January 15, 1902) was an American zoologist and palaeontologist. Biography Alpheus Hyatt II was born in Washington, D.C. to Alpheus Hyatt and Harriet Randolph (King) Hyatt. He briefly attended the Maryland Military Academy and Yale University, and after graduating from Harvard University in 1862, he enlisted as a private in the Massachusetts Volunteer Infantry for the Civil War, emerging with the rank of captain. After the war he worked for a time at the Essex Institute (now the Peabody Essex Museum in Salem, Massachusetts. He and a colleague founded ''American Naturalist'' and Hyatt served as editor from 1867 to 1870. He became a professor of paleontology and zoology at Massachusetts Institute of Technology in 1870, where he taught for eighteen years, and was professor of biology and zoology at Boston University from 1877 until his death in 1902. He also served as curator of the Boston Society of Natural History, where his longtime a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by '' Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Cephalopod")
