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Placenticeras Meeki
''Placenticeras meeki'' is an ammonite species from the Late Cretaceous. These cephalopods were fast-moving nektonic carnivores. They mainly lived in the American Interior Basin (Western Interior Seaway). Description Shells of this species could reach a diameter of about . They are discoidal, involute and compressed. Whorls are stout and rounded to diameter of 3 millimeters. The surface of fossils is usually covered by opalized nacre (ammolite). Etymology The name honours Fielding Bradford Meek Fielding Bradford Meek (December 10, 1817 – December 22, 1876) was an American geologist and a paleontologist who specialized in the invertebrates. Biography The son of a lawyer, he was born in Madison, Indiana. In early life he was in bu .... References Ammonites* J.B. ReesidA comparison of the genera Metaplacenticeras Spath and Platcenticeras MeekProfessional Paper - United States Geological Survey *Sepkoski, Jac Sepkoski's Online Genus Database – Cephalopodes Placentic ... [...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 and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Museo Civico Di Storia Naturale Di Milano
The Museo Civico di Storia Naturale di Milano (Milan Natural History Museum) is a museum in Milan, Italy. It was founded in 1838 when naturalist Giuseppe de Cristoforis donated his collections to the city. Its first director was Giorgio Jan. The Museum is located within a 19th-century building in the Indro Montanelli Garden, near the historic city gate of Porta Venezia. The structure was built between 1888 and 1893 in Neo-Romanesque style with Gothic elements. The museum is divided into five different permanent sections: Mineralogy (with a large collection of minerals from all over the world); Paleontology (with several fossils of dinosaurs and other prehistoric organisms); Natural History of Man (dedicated to the origins and evolution of humans with a particular attention to the relationship of the latter with the environment); Invertebrate Zoology (dedicated to mollusks, arthropods and entomology); and Vertebrate Zoology (dedicated to vertebrates, both exotic and Europea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Böhm
Johannes Böhm (1857–1938) was a German geologist and palaeontologist. He was a researcher in the Prussian Geological Institute in Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ... ( Preußische Geologische Landesanstalt) Works partial list *''Der Grünsand von Aachen und seine Molluskenfauna Bonn, Universitäts'' Bonn, Buchdruckerei von C. Georgi,1885online*''Die Fossilien von Java auf Grund einer Sammlung von Dr. R.D.M. Verbeek und von Anderen – Die Mollusken der Njalindungsschichten, Schluss: Echinodermata und Arthropoda''. with K. Martin and H. Gerth. Leiden, Brill, 1909.Series:Sammlungen des Geologischen Reichs-Museums in Leiden, n.F, Bd.1, Abt.2, Heft 4 *''Über die obertriadische Fauna der Bäreninsel'' Stockholm, kungl. Boktryckeriet, 1903. *''Geologie und palà ... [...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 near Pomp ... [...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] |
Nektonic
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms that were carried along by the current, the plankton. As a guideline, nektonic organisms have a high Reynolds number (greater than 1000) and planktonic organisms a low one (less than 10). However, some organisms can begin life as plankton and transition to nekton later on in life, sometimes making distinction difficult when attempting to classify certain plankton-to-nekton species as one or the other. For this reason, some biologists choose not to use this term. History The term was first proposed and used by the German biologist Ernst Haeckel in 1891 in his article ''Plankton-Studien'' where he contrasted it with plankton, the aggregate of passively floating, drifting, or somewhat motile organisms present in a body of water, primarily t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea, which existed from the early Late Cretaceous (100 million years ago) to the earliest Paleocene (66 Ma), connected the Gulf of Mexico, through the United States and Canada, to the Arctic Ocean. The two land masses it created were Laramidia to the west and Appalachia to the east. At its largest extent, it was deep, wide and over long. Origin and geology By Late-Cretaceous times, Eurasia and the Americas had separated along the south Atlantic, and subduction on the west coast of the Americas had commenced, resulting in the Laramide orogeny, the early phase of growth of the modern Rocky Mountains. The Western Interior Seaway may be seen as a downwarping of the continental crust ahead of the growing Laramide/Rockies mountain chain. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammolite
Ammolite is an opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral contained in nacre, with a microstructure inherited from the shell. It is one of few Biogenic substance, biogenic gemstones; others include amber and pearl.#Notes, 1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation (CIBJO), the same year commercial mining of ammolite began. It was designated the official gemstone of the Lethbridge, City of Lethbridge, Alberta in 2007. Ammolite is also known as ''aapoak'' (Kainah for "small, crawling stone"), gem ammonite, calcentine, and Korite. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite. Marcel Charbonneau and his business partner Mike Berisoff were the first to create commercial Doublet (lapidary), doublets of the gem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fielding Bradford Meek
Fielding Bradford Meek (December 10, 1817 – December 22, 1876) was an American geologist and a paleontologist who specialized in the invertebrates. Biography The son of a lawyer, he was born in Madison, Indiana. In early life he was in business as a merchant, but he became deaf and spent his leisure hours were devoted to collecting fossils and studying the rocks of the neighborhood of Madison. Being unsuccessful in business with delicate health he turned his whole attention to science, and in 1848 he gained employment on the United States Geological and Geographical Survey of the Territories as an assistant to D. D. Owen in Iowa, and subsequently in Wisconsin and Minnesota. In 1852 he became assistant to Professor James Hall at Albany, New York, and worked at palaeontology with him until 1858. He received training in illustration from Frederick Swinton. Meanwhile, in 1853 he accompanied FV Hayden in an exploration of the badlands of Dakota and brought back valuable collec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placenticeratidae
Placenticeratidae is an extinct family of mostly Late Cretaceous ammonites ( cephalopod order Ammonitida) included in the superfamily Hoplitoidea, derived from the Engonoceratidae by an increase in suture complexity. Placeticeratids are characterized by rather involute compressed shells of moderate to large size with narrow flat or grooved venters (outer rims), at least on early whorls. Most are rather smooth or weakly ornamented except for a few later forms in which the outer whorls are strongly tuberculate. The suture has numerous, including auxiliary and adventive, elements. Saddles and lobes are typically deep, narrow necked, and raggedly embayed. The Placenticeratidae had their beginning in the Late Albian stage at the end of the Early Cretaceous, starting with '' Hypengonoceras''. The type genus, '' Placenticeras'', appears later and is known from the upper Santonian to the lower Campanian of the Upper Cretaceous. The family has the longest duration of the Hoplitaceae, exte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
