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45-575: The type locality of the unit is in Ventura County , on the east side of Rincon Mountain, where the formation is exposed in the south-flowing Los Sauces Canyon, north of U.S. Highway 101 and in the vicinity of the Rincon Oil Field . The unit is mapped from Ventura County westward along the south slope of the Santa Ynez Mountains, as well as on portions of the north slope. It also occurs in

90-538: A circulatory system where hemolymph sinuses absorbs oxygen through special areas on the inner wall of the carapace. In addition, the respiratory protein hemocyanin has been found in the two orders Myodocopida and Platycopida. Nitrogenous waste is excreted through glands on the maxillae, antennae, or both. The primary sense of ostracods is likely touch, as they have several sensitive hairs on their bodies and appendages. Compound eyes are only found in Myodocopina within

135-710: A few places north of the Santa Ynez Fault, but outcrops nowhere north of the Santa Ynez River . In the subsurface it frequently is found in well cores, underlying the Monterey Formation and overlying the Vaqueros Formation . At the ground surface, the contact with the Vaqueros is obvious along the south slope of the mountains, for it is almost always defined by the line dividing the rounded, grassy foothills from

180-483: A light organ in which they produce luminescent chemicals. These ostracods are called "blue sand" or "blue tears" and glow blue in the dark. Their bioluminescent properties made them valuable to the Japanese during World War II , when the Japanese army collected large amounts from the ocean to use as a convenient light for reading maps and other papers at night. The light from these ostracods, called umihotaru in Japanese,

225-469: A structure is poorly ventilated – such as when the windows remain shut during the cool season – radon can accumulate to a hazardous level. Some of the mitigation measures employed in houses on the Rincon Formation since the discovery of the problem in the 1990s include building ventilation systems for the air space beneath the structure, performing "soil suction" in which the gas is pulled directly from

270-465: A water current between the body and the inner surface of the carapace. Podocopa, the largest subclass, have no gills, heart or circulatory system, so the gas exchange take place all over the surface. The other subclass of ostracods, the Myodocopa, do have a heart, and the family Cylindroleberididae also have 6-8 lamellar gills. Certain other larger members of Myodocopa, even if they don't have gills, have

315-538: Is eight or nine (but family Entocytheridae and suborder Bairdiocopina has only seven), the Halocyprida goes through six or seven, and Myodocopida only four to six. They are able to produce several offspring many times as adults ( iteroparity ). A variety of fauna prey upon ostracods in both aquatic and terrestrial environments. An example of predation in the marine environment is the action of certain Cytherocopina in

360-467: Is encased by a carapace originating from the head region, and consists of two valves superficially resembling the shell of a clam. A distinction is made between the valve (hard parts) and the body with its appendages (soft parts). Studies of the embryonic development in Myodocopida shows that the bivalved carapace develops from two independent buds of the carapace valves. As the two halves grows, they meet in

405-456: Is in development called mutual ostracod temperature range (MOTR), similar to the mutual climatic range (MCR) used for beetles, which can be used to infer palaeotemperatures. The ratio of oxygen-18 to oxygen-16 (δ18O) and the ratio of magnesium to calcium (Mg/Ca) in the calcite of ostracod valves can be used to infer information about past hydrological regimes, global ice volume and water temperatures. Ecologically, marine ostracods can be part of

450-449: Is known from humid forest soils of South Africa , Australia and New Zealand . As of 2008, around 2000 species and 200 genera of non-marine ostracods are found. However, a large portion of diversity is still undescribed, indicated by undocumented diversity hotspots of temporary habitats in Africa and Australia. Non-marine species have been found to live in sulfidic cave ecosystems such as

495-441: Is no larval stage or metamorphosis ( direct development ). Instead they hatch from the egg as juveniles with the bivalved carapace and at least three functional limbs. As the juvenile grows through a series of molts they acquire more limbs and develop further the already existing ones. They reach sexual maturity in the final instar and then never molts again. The number of instars they go through before adulthood varies. In Podocopa it

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540-518: Is the type locality. The concept is similar to type site in archaeology . Ostracod Ostracods , or ostracodes, are a class of the Crustacea (class Ostracoda ), sometimes known as seed shrimp . Some 33,000 species (only 13,000 of which are extant ) have been identified, grouped into 7 valid orders. They are small crustaceans, typically around 1 mm (0.04 in) in size, but varying from 0.2 to 30 mm (0.008 to 1 in) in

585-653: Is typically capped not by the Monterey but by the Temblor Formation , a sandstone similar to the underlying Vaqueros; additionally, north of the river the Rincon Formation grades into this sandstone to the east. Northeast of Blue Canyon and the Little Pine Fault, in the backcountry of easternmost Santa Barbara County and Ventura County, the Rincon Formation disappears, and the Temblor Formation rests unconformably on

630-488: The Guinness World Record for the oldest penis. Males had observable sperm that is the oldest yet seen and, when analysed, showed internal structures and has been assessed as being the largest sperm (per body size) of any animal recorded. It was assessed that the fossilisation was achieved within several days, due to phosphorus in the bat droppings of the cave where the ostracods were living. The body of an ostracod

675-561: The Movile Cave , deep groundwaters, hypersaline waters, acidic waters with pH as low as 3.4, phytotelmata in plants like bromeliads , and in temperatures varying from almost freezing to more than 50 °C in hot springs. Of the known specific and generic diversity of non-marine ostracods, half (1000 species, 100 genera) belongs to one family (of 13 families), Cyprididae . Many Cyprididae occur in temporary water bodies and have drought-resistant eggs, mixed/ parthenogenetic reproduction, and

720-572: The North American and Pacific Plates , shortly after the Farallon Plate had been completely buried beneath the American plate. At that time only clay- and mud-sized grains could reach the deposition location, since it was far from the shore, and sediment accumulated slowly. The unit represents a period of around 7.5 million years – from 24 Ma (million years before present) to 17.5 – covering, with

765-738: The biozonation of marine strata on a local or regional scale, and they are invaluable indicators of paleoenvironments because of their widespread occurrence, small size, easily preservable, generally moulted, calcified bivalve carapaces; the valves are a commonly found microfossil . A find in Queensland, Australia in 2013, announced in May 2014, at the Bicentennary Site in the Riversleigh World Heritage area, revealed both male and female specimens with very well preserved soft tissue. This set

810-431: The cuspidariid clams in detecting ostracods with cilia protruding from inhalant structures, thence drawing the ostracod prey in by a violent suction action. Predation from higher animals also occurs; for example, amphibians such as the rough-skinned newt prey upon certain ostracods. Whale sharks also seem to eat them as part of their filter feeding process. Some ostracods, such as Vargula hilgendorfii , have

855-408: The zooplankton or (most commonly) are part of the benthos , living on or inside the upper layer of the sea floor. Ostracods has been found as deep as 9,307 m (genus Krithe in family Krithidae ). Subclass Myodocopa and the two podocop orders Palaeocopida and Platycopida are restricted to marine environments (except for Platycopida which have a few brackish species), but we find non-marine forms in

900-457: The 4 pCi/L level, and 2 per 1000 at the average indoor radon level in the United States of 1.3 pCi/L. Smokers were at a much greater risk, with fully 260 out of 1,000 expected to die of lung cancer with a lifetime exposure of 20 pCi/L of radon. Radon migrates upwards from its source, entering buildings wherever the bottom is imperfectly sealed, for example through cracks in a concrete slab. If

945-536: The Hondo Offshore Oil Field the thickness is around 600 feet, while in the abandoned Coal Oil Point field it is 900 feet, and in the Cuarta Offshore Oil Field it is over 1200 feet thick. The Rincon Formation is massive to poorly bedded, and consists of predominantly argillaceous to silty shale and mudstone, with occasional dolomite . Two layers of siliceous shale are found in the middle of

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990-420: The Myodocopa. The order Halocyprida in the same subclass is eyeless. Podocopid ostracods have just a naupliar eye consisting of two lateral ocelli and a single ventral ocellus, but the ventral one is absent in some species. Platycopida was assumed to be completely eyeless, but two species, Keijcyoidea infralittoralis and Cytherella sordida, have been found to both possess a nauplius eye too. A new method

1035-417: The Rincon Formation, or on alluvium or soils derived from the Rincon Formation, showed interior radon concentrations in excess of 4 picocuries per liter (pCi/L), the U.S. EPA action level, and 26% had measured levels of radon over 20 pCi/L. According to the U.S. EPA, non-smokers exposed to radon at the 20 pCi/L level over a lifetime had a risk of dying from lung cancer at 36 in 1000, as opposed to 7 in 1000 at

1080-531: The Vaqueros Formation, the entirety of the lower Miocene. The Rincon Formation weathers to a distinctive loamy, black soil with a high expansion-contraction potential, presenting a risk to structures built on soils derived from the formation. Landslides and slumps are frequent on soils produced from the Rincon, although they usually are not large, limited to about 15 feet in depth. As is common with shale units,

1125-495: The ability to swim. These biological attributes preadapt them to form successful radiations in these habitats. Male ostracods have two penises , corresponding to two genital openings ( gonopores ) on the female. The individual sperm are often large, and are coiled up within the testis prior to mating; in some cases, the uncoiled sperm can be up to six times the length of the male ostracod itself. Mating typically occurs during swarming, with large numbers of females swimming to join

1170-399: The case of the marine Gigantocypris . The largest known freshwater species is Megalocypris princeps , which reach 8 mm in length. In most cases, their bodies are flattened from side to side and protected by a bivalve -like valve or "shell" made of chitin , and often calcium carbonate. The family Entocytheridae and many planktonic forms do not have calcium carbonate. The hinge of

1215-630: The eggs are released directly into the sea, except for a single genus with brood care. In the subclass Podocopa, brood care is only found in Darwinulocopina and some Cytherocopina in the order Podocopida. In the remaining Podocopa it is common to glue the eggs to a firm surface, like vegetation or the substratum. These eggs are often resting eggs, and remain dormant during desiccation and extreme temperatures, only hatching when exposed to more favorable conditions. Species adapted to vernal pools can reach sexual maturity in just 30 days after hatching. There

1260-652: The female is able to read the display to pinpoint the male's location. In one species hundreds of thousands of males synchronize their light display, and when one male creates a pattern of light, the new pattern will spread out as the neighboring males repeat it. Early work indicated that Ostracoda may not be monophyletic , and early molecular phylogeny was ambiguous on this front. Recent combined analyses of molecular and morphological data suggested monophyly in analyses with broadest taxon sampling, but this monophyly had no or very little support (Fig. 1 - bootstrap 0, 17 and 46, often values above 95 are considered sufficient for

1305-507: The formation has a low permeability, and therefore where oil and gas reservoirs occur in the area it serves as the impermeable cap keeping the hydrocarbons in place. Some of these reservoirs include the Ellwood Oil Field , Gaviota Offshore Gas Field, Cuarta Offshore Oil Field, Molino Gas Field, and others. Microfossils are common in the Rincon, and have been helpful in dating the unit. Formaniferal remains in particular are abundant, and

1350-569: The four superfamilies Terrestricytheroidea, Cypridoidea, Darwinuloidea, and Cytheroidea in the order Podocopida . Terrestricytheroidea is semi-terrestrial and usually found in brackish and marine-influenced environments such as salt marshes, but not in freshwater. The other three superfamilies also live in freshwater (Darwinuloidea is exclusively non-marine). Of these three, only Cypridoidea have freshwater species able to swim. Representatives living in terrestrial habitats are also found in all three freshwater groups, such as genus Mesocypris which

1395-767: The male of at least 75 known species of the Cypridinidae, restricted to the Caribbean, use pulses of light to attract females. Some species are the opposite where the females use pulses of light to attract males. This is seen in one example such as the glow worm . This bioluminiscent courtship display has only evolved once in ostracods, in a cypridinid group named Luxorina that originated at least 151 million years ago. Ostracods with bioluminescent courtship show higher rates of speciation than those who simply use light as protection against predators. The male will continue to swim after releasing its small ball of bioluminescent mucus, but

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1440-415: The males. Some species are partially or wholly parthenogenetic . Superfamily Darwinuloidea was assumed to have reproduced asexually for the last 200 million years, but rare males have since been discovered in one of the species. In the subclass Myodocopa, all members of the order Myodocopida have brood care, releasing their offspring as first instars, allowing a pelagic lifestyle. In the order Halocyprida

1485-413: The middle. In Manawa, an ostracod in the order Palaeocopida, the carapace originates as a single element and during growth folds at the midline. The body consists of a head and thorax , separated by a slight constriction. Unlike many other crustaceans, the body is not clearly divided into segments . Most species have completely or partly lost their trunk segmentation, and there are no boundaries between

1530-523: The more rugged, chaparral-covered sandstones upslope. Thickness of the unit at the surface ranges from about 1400 to 1700 feet south of the mountain crest, averaging 1600 feet. It is less thick north of the mountains, attaining a maximum thickness of around 1000 feet at the western end of its range, and thinning to the east. In the subsurface under the Santa Barbara Channel the thickness is variable but generally less than onshore. In well cores in

1575-456: The most common arthropods in the fossil record" with fossils being found from the early Ordovician to the present. An outline microfaunal zonal scheme based on both Foraminifera and Ostracoda was compiled by M. B. Hart. Freshwater ostracods have even been found in Baltic amber of Eocene age, having presumably been washed onto trees during floods. Ostracods have been particularly useful for

1620-458: The much older Cozy Dell Shale . The Rincon Shale was deposited on the deep sea floor during the time at which the Miocene sea reached its greatest depth. The faunal assemblage found as fossils and fragmentary fossils indicates that the sea was tropical to subtropical at this time. During this period the sea deepened due to tectonic forces, as the area of deposition was at the collision boundary of

1665-463: The second and third pair are absent in suborder Cladocopina . In the Myodocopina the third pair is a multisegmented cleaning organ that resembles a worm. Their external genitals seem to originate from the fusion of three to five appendages. The two "rami", or projections, from the tip of the tail point downward and slightly forward from the rear of the shell. All ostracods have a pair of "ventilatory appendages" that beat rhythmically, which create

1710-423: The soil under the building, and active house pressurization, which keeps the gas from entering. Type locality (geology) Type locality , also called type area , is the locality where a particular rock type , stratigraphic unit or mineral species is first identified. If the stratigraphic unit in a locality is layered, it is called a stratotype , whereas the standard of reference for unlayered rocks

1755-421: The thorax and abdomen , and it has therefore been impossible to tell if the first pair of limbs after the maxillae belongs to the head or the thorax. With a few exception, like platycopids which have an 11-segmented trunk, the abdomen in ostracods has no visible segments. The head is the largest part of the body, and bears four pairs of appendages. Two pairs of well-developed antennae are used to swim through

1800-504: The two valves is in the upper (dorsal) region of the body. Ostracods are grouped together based on shell and soft part morphology, and molecular studies have not unequivocally supported the group's monophyly . They have a wide range of diets, and the class includes carnivores, herbivores, scavengers and filter feeders, but most ostracods are deposit feeders. Ostracod comes from the Greek óstrakon meaning shell or tile. Ostracods are "by far

1845-461: The unit, and they outcrop noticeably in the region west of Goleta. The base of the unit, which rests conformably on the shallower-water Vaqueros Formation, contains a glauconitic layer. Several thin layers of bentonite occur within the unit, and the unit is capped by one as well, which forms the base of the conformably overlying Monterey Formation . North of the Santa Ynez River, the Rincon

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1890-477: The various types have allowed staging of the layers into Upper Zemorrian and Lower and Upper Saucesian. Within Santa Barbara County, two significant fossil finds (aside from microfossils) have been made in the Rincon Formation. In Ventura County, the exposure of the formation along Los Sauces Creek has yielded ten different species of ostracoda ; a detailed study suggested that the sea bottom they inhabited

1935-463: The water. In addition, there are a pair of mandibles and a pair of maxillae . The thorax has three primary pairs of appendages. The first of these has different functions in different groups. It can be used for feeding (Cypridoidea) or for walking (Cytheroidea), and in some species it has evolved into a male clasping organ. The second pair is mainly used for locomotion, and the third is used for walking or cleaning, but can also be reduced or absent. Both

1980-586: Was around 2,000 meters deep, very near to the edge of the continental shelf . Naturally high in uranium, the Rincon Formation is a notorious source of radon gas emissions in Santa Barbara and Ventura Counties, making them the counties with the greatest radon hazard in California. Radon is a byproduct of radioactive decay of uranium, which is present in the Rincon at around 20 to 30 parts per million (ppm). A 1993 study found that approximately 74% of homes built on

2025-519: Was sufficient to read by but not bright enough to give away troops' position to enemies. Bioluminescence has evolved twice in ostracods; once in Cypridinidae , and once in Halocyprididae . In bioluminescent Halocyprididae a green light is produced within carapace glands, and in Cypridinidae a blue light is produced and extruded from the upper lip. Most species use the light as predation defense, but

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