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Macrarene Diegensis
''Macrarene diegensis'' is a fossil species of small sea snail, a marine gastropod mollusk in the family Liotiidae. Description The height of the shell attains 20 mm, its diameter 25 mm. The narrowly umbilicated shell contains 4 whorls with distinct sutures and a projecting peripheral keel. The oblique aperture is circular. Its color is chalky white. This fossil species shows some similarities with '' Macrarene coronadoensis'' and ''Macrarene californica''. Distribution This species is known only as a fossil. It is found in the San Diego Formation, California, and dates from the Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
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''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the abs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of Taxonomy (biology), 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 reproduction, produce Fertility, fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology (biology), 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 binomial nomenclature, 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 specifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the absence of a visible shell. Definition Determining whether some gastropods should be called sea snails is not always easy. Some species that live in brackish water (such as certain neritids) can be listed as either freshwater snails or marine snails, and some species that live at or just above the high tide level (for example species in the genus '' Truncatella'') are sometimes considered to be sea snails and sometimes listed as land snails A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known .... Anatomy Sea snails are a very large group o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine (ocean)
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the world ocean is conventionally divided."Ocean." ''Merriam-Webster.com Dictionary'', Merriam-Webster, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. 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. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. 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 invertebrate species. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liotiidae
Liotiidae is a family of small sea snails, marine gastropod mollusks in the clade Vetigastropoda (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Gofas, S. (2013). Liotiidae Gray, 1850. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=196896 on 2013-09-07 Description The head of the animal is proboscidiform. The epipodial line has a pair of conical lobes and three pairs of cirri. The white shell has a turbiniform or discoidal shape. It shows longitudinal ribs or is clathrate. The shell shows a fine lamellar sculpture. The circular aperture is feebly nacreous. The thick peristome is continuous and shows a callous varix. The multispiral operculum is hispid, corneous and has a soft, calcareous outer layer (intritacalx) formed of pearly beads that are disposed spirally. Taxonomy 2005 taxonomy The family Liotiidae belongs to the superfamily Turbinoidea, according to the taxonomy of the G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in numerous gastropods, but it is also found in shelled cephalopods including '' Nautilus'', '' Spirula'' and the large extinct subclass of cephalopods known as the ammonites. A spiral shell can be visualized as consisting of a long conical tube, the growth of which is coiled into an overall helical or planispiral shape, for reasons of both strength and compactness. The number of whorls which exist in an adult shell of a particular species depends on mathematical factors in the geometric growth, as described in D'Arcy Wentworth Thompson's classic 1917 book '' On Growth and Form'', and by David Raup. The main factor is how rapidly the conical tube expands (or flares-out) over time. When the rate of expansion is low, such that each subsequent whorl is not that much wider than the previous one, then the adult shell has numerous whorl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrarene Coronadoensis
''Macrarene coronadoensis'' is a species of sea snail, a marine gastropod mollusk in the family Liotiidae.Rosenberg, G. (2012). ''Macrarene coronadoensis'' Stohler, 1959. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=593052 on 2012-12-03 Description The height of the shell attains 23.2 mm., its diameter 26.9 mm. The nacreous white shell is rather large for the genus and contains 3½ rapidly enlarging whorls. The whorls have a smooth surface. The body whorl and the preceding whorl show two parallel rows of short projections. These are quite distinct and equally strong. Each row contains between 7 and 12 projections (in most cases 9 or 10). These projections don't point upward but project horizontally. The second row of projections below the periphery distinguishes this species from Macrarene farallonensis. There is no pronounced axial sculpture on the base of the shell. The aperture is circular. Inside it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrarene Californica
''Macrarene californica'', common name the Californian liotia, is a species of sea snail, a marine gastropod mollusk in the family Liotiidae.Rosenberg, G. (2012). ''Macrarene californica'' (Dall, 1908). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=575693 on 2012-12-03 Description (Original description by W.H. Dall) The height of the shell attains 15 mm, its diameter 23 mm. The rude, yellowish-white shell is large for the genus. It has a depressed shape with about six whorls, carrying at the shoulder six blunt, large, projecting tubercles. The nucleus is small, the nepionic whorls reticulate and flattened. The later whorls are keeled bluntly at the shoulder, behind which they are flattened. On the flat area are two strong, elevated, spiral threads (which later disappear) close together, with the channels on either side reticulated by subequal and subequally spaced radial threads. On the body whorl all the sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Diego Formation
The San Diego Formation is a geologic formation in southwestern San Diego County in southern California (United States), and northwestern Baja California (México). Geology It is a coastal transitional marine and non-marine pebble and cobble conglomerate deposit and marine sandstone rock with marine fossils, from a former bay, deposited during the Middle Pliocene to Late Pliocene ages (2–3 million years ago), of the Pliocene period during the Cenozoic Era. This formation is found from the south side of Mount Soledad in San Diego County to Rosarito Beach in northern Baja California, including Tijuana, Mexico, and the southwestern corner of San Diego County from San Ysidro to Pacific Beach. San Diego Formation deposits were formed in a large, open, crescent-shaped bay similar in size to Monterey Bay that existed on the coast in Pliocene times. Aquifer The formation contains the San Diego Formation Basin, a large aquifer under Imperial Beach, Chula Vista, National City, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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