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Aptychus Limestone
An aptychus is a type of marine fossil. It is a hard anatomical structure, a sort of curved shelly plate, now understood to be part of the body of an ammonite. Paired aptychi have, on rare occasions, been found at or within the aperture of ammonite shells. The aptychus was usually composed of calcite, whereas the ammonite shell was aragonite. Aptychi can be found well-preserved as fossils but usually quite separate from ammonite shells. This circumstance led to them being initially classified as valves of bivalves (clams), which they do somewhat resemble. Aptychi are found in rocks from the Devonian period through to those of the Cretaceous period. There are many forms of aptychus, varying in shape and in the sculpture of the inner and outer surfaces. However, because they are so rarely found in position within the ammonite shell, it is often unclear which kind of aptychus belonged to which species of ammonite. When only a single plate is present, as is sometimes the case, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symmetry, bilateral body symmetry, a prominent head, and a set of cephalopod arm, arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt Cephalopod ink, 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 taxon, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by ''Nautilus (genus), Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solnhofen Limestone
The Solnhofen Limestone or Solnhofen Plattenkalk, formally known as the Altmühltal Formation, is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies. The most familiar fossils of the Solnhofen Plattenkalk include the early feathered theropod dinosaur ''Archaeopteryx'' preserved in such detail that they are among the most famous and most beautiful fossils in the world. The Solnhofen beds lie in the German state of Bavaria (Bayern), halfway between Nuremberg (Nürnberg) and Munich (München) and were originally quarried as a source of lithographic limestone. The Jura Museum situated in Eichstätt, Germany has an extensive exhibit of Jurassic fossils from the quarries of Solnhofen and surroundings, including marine reptiles, pterosaurs, and one specimen of the early bird ''Archaeopteryx''. Paleoenvironment and preservation During the Late Jurassic, this a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perisphinctes
''Perisphinctes'' is an extinct genus of ammonite cephalopod. They lived during the Middle to Late Jurassic epochs and serve as an index fossil Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ... for that time period. The species ''P. boweni'' was named after the English chemist and geologist E. J. Bowen (1898–1980). Distribution Cephalopods of species belonging to this genus have been found in the Jurassic of Antarctica, Argentina, Chile, Cuba, Egypt, Ethiopia, France, Germany, Hungary, India, Iran, Italy, Japan, Madagascar, Poland, Portugal, Russia, Saudi Arabia, Spain, Switzerland, the United Kingdom and Yemen. Gallery File:Perisphinctes (Prosososphinctes) virguloides (Waagen).jpg, ''Perisphinctes virguloides'' File:Perisphinctes cf choffati.JPG, '' Perisphinctes choffati'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laevaptychus
''Laevapetchyus'' is a genus of ammonites. In Europe, most representatives of the genus ''Laevaptychus'' occur by the end of the early Tithonian. ''Laevaptychus latus'' is common throughout the Upper Jurassic and is abundant in the Alpine-Mediterranean region. It is also recorded in southern Arabia, Tunisia, Somalia and the western North Atlantic. In Mexico, the first records of ''Aptychus latus'' (= ''Laevaptychus latus'') are provided from the Upper Jurassic of the La Caja Formation at Sierra de Catorce, San Luis Potosí and from the upper Kimmeridgian "Couche à ''Haploceras'' d. gr. ''Fialar''" of Sierra de Santa Rosa, Mazapil, Zacatecas Zacatecas, officially the Free and Sovereign State of Zacatecas, is one of the Political divisions of Mexico, 31 states of Mexico. It is divided into Municipalities of Zacatecas, 58 municipalities and its capital city is Zacatecas City, Zacatec .... References {{Taxonbar, from=Q28432804 Ammonitida genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautilus
A nautilus (; ) is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina. It comprises nine living species in two genera, the type genus, type of which is the genus ''Nautilus (genus), Nautilus''. Though it more specifically refers to the species ''chambered nautilus, Nautilus pompilius'', the name chambered nautilus is also used for any of the Nautilidae. All are protected under CITES CITES Appendix II, Appendix II. Depending on species, adult shell diameter is between . The Nautilidae, both extant and extinct, are characterized by involute or more or less convoluted shells that are generally smooth, with compressed or depressed whorl (mollusc), whorl sections, straight to sinuous Suture (anatomy), sutures, and a tubular, generally central siphuncle.Kümmel, B. 1964. Nautiloidae-Nautilida, in the Treatise on Invertebrate Paleontology, Geological Society of America and Univ of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (animal)
An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal. Examples include: * An operculum (gastropod), a single lid that (in its most complete form) closes the aperture of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. The operculum lies on the top rear part of the foot. When the foot is retracted, the operculum is rotated 180° and closes the shell. * An operculum (fish), a flap that covers the gills in bony fishes and chimaeras. * The cover that rapidly opens a cnida of a cnidarian such as a jellyfish or a sea anemone. The lid may be a single hinged flap or three hinged flaps arranged like slices of pie. * In insects, the operculum is the name for one or more lids covering the tympanal cavity. A subgenital operculum is exhibited in stick ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror Image
A mirror image (in a plane mirror) is a reflection (physics), reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical phenomenon, optical effect, it results from specular reflection off from surfaces of lustrous materials, especially a mirror or water. It is also a concept in geometry and can be used as a conceptualization process for 3D structures. In geometry and geometrical optics In two dimensions In geometry, the mirror image of an object or 2D geometric model, two-dimensional figure is the virtual image formed by reflection (mathematics), reflection in a plane mirror; it is of the same size as the original object, yet different, unless the object or figure has reflection symmetry (also known as a P-symmetry). Two-dimensional mirror images can be seen in the reflections of mirrors or other reflecting surfaces, or on a printed surface seen inside-out. If we first look at an obje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod Beak
All extant taxon, extant cephalopods have a two-part beak, or Rostrum (anatomy), rostrum, situated in the buccal mass and surrounded by the muscular Cephalopod limb, head appendages. The Dorsal (anatomy), dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion.Young, R.E., M. Vecchione & K.M. Mangold (1999)Cephalopoda Glossary Tree of Life Web Project. The beak may also be referred to as the mandibles or jaws.Tanabe, K., Y. Hikida & Y. Iba (2006). Two coleoid jaws from the Upper Cretaceous of Hokkaido, Japan. ''Journal of Paleontology'' 80(1): 138–145. These beaks are different from Beak, bird beaks because they crush bone while most bird beaks do not. Fossilized remains of beaks are known from a number of cephalopod-groups, both extant and extinct, including squids, octopus, octopodes, belemnites, and vampyromorphs. Aptychus, Aptychi - paired plate-like structures found in ammonites - may also have been jaw elements. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonellites Latus
''Trigonellites'' is an extinct genus of basal ammonite, known from two or three species, discovered in outcrops of the Late Jurassic-aged Kimmeridge Clay Formation in Ely and Cumnor, England and possibly also an unnamed Early Triassic-aged rock formation in Bindlach, Germany. J. Prestwich. (1879). On the discovery of a species of ''Iguanodon'' in the Kimmeridge Clay near Oxford; and a notice of a very fossiliferous band of the Shotover Sands. ''Geological Magazine, new series, decade'' 2 6(5):193-195 It was originally classified as a bivalve,G. A. Goldfuss. (1863). Abbildungen und Beschreibungen der Petrefacten Deutschlands und der angrenzenden Länder. Divisio Quarta: Molluscorum acephalicorum reliquiae. Muschelthiere der Vorwelt. 1. Bivalvia. ''Petrefacta Germaniae'' 4(1):1-273 but it has since been classed as an ammonite species. Only two species once placed in the genus are still considered valid today: ''T. latus'' and ''T. curvirostris'', with one dubious species, ''T. sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusk
Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The number of additional fossil species is estimated between 60,000 and 100,000, and the proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat, as numerous groups are freshwater and even terrestrial species. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known extant i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
