The Ziliujing Formation is a geological formation in China , It is Early Jurassic in age. It is part of the stratigraphy of the Sichuan Basin . The dinosaur Gongxianosaurus and indeterminate theropod material are known from the Dongyuemiao Member of the formation, as well as dinosaur footprints, Zizhongosaurus and indeterminate prosauropods from the Da'anzhai Member. The basal sauropod Sanpasaurus is known from the Maanshan Member. An possible unnamed stegosaur and the pliosauroid plesiosaur Sinopliosaurus are also known from this formation but they were found an indeterminate member. An unnamed teleosaurid known from a complete skull has also been found in the formation, pending a formal description. The deposition environment during the Da'anzhai Member in the lower Toarcian is thought to have been that of a giant freshwater lake encompassing the whole of the Sichuan basin, around 3 times larger than Lake Superior , coeval with the Toarcian Oceanic Anoxic Event around 183 Ma. The Sinemurian-Pliensbachian boundary event (192.9 Ma) has been recorded on the top of the Dongyuemiao Member, while lower parts of this member are of Earliest Sinemurian age (around 199 Ma).
16-393: Acuneopsis Isolated Shells A freshwater mussel, considered a member of the family Unionidae inside Unionida . Ecological indicator of shallow zone of the big fresh-water lake under a hot climate Apseudocardinia Isolated Shells A freshwater clam, member of the family Pseudocardiniidae inside Trigoniida . Cuneopsis Isolated Shells A freshwater mussel, member of
32-729: A female-like open-reading frame dubbed hermaphroditic open-reading frame (H-ORF). In many mussels, the hermaphroditic state is ancestral and the male sex evolved later. This region of the mitochondria also may be responsible for the evolution of doubly uniparental inheritance seen in freshwater mussels. The following classification is based on MolluscaBase and the MUSSEL Project database: Widespread Africa Central America and Mexico Eastern Asia Europe India Middle East New Guinea North America In large enough quantities, unionid shells can have enough of an impact on environmental conditions to affect
48-441: A small fish complete with markings and false eyes. This decoy moves in the current and attracts the attention of real fish. Some fish see the decoy as prey, while others see a conspecific , i.e. a member of their own species. Whatever they see, they approach for a closer look and the mussel releases huge numbers of larvae from her gills, dousing the inquisitive fish with her tiny, parasitic young. These glochidial larvae are drawn into
64-654: A wide range of habitats, but most often occupy lotic waters, i.e. flowing water such as rivers, streams and creeks. The recent phylogenetic study reveals that the Unionidae most likely originated in Southeast and East Asia in the Jurassic, with the earliest expansions into North America and Africa (since the mid-Cretaceous) followed by the colonization of Europe and India (since the Paleocene). Unionidae burrow into
80-407: Is ejected from the mantle cavity through the male's excurrent aperture and taken into the female's mantle cavity through the incurrent aperture. Fertilised eggs move from the gonads to the gills ( marsupia ) where they further ripen and metamorph into glochidia , the first larval stage. Mature glochidia are released by the female and then attach to the gills , fins, or skin of a host fish . A cyst
96-469: Is quickly formed around the glochidia, and they stay on the fish for several weeks or months before they fall off as juvenile mussels , which then bury themselves in the sediment. Some of the species in the Unionidae, notably in the Lampsilini tribe, have evolved a remarkable reproductive strategy. The edge of the female's body that protrudes from the valves of the shell develops into an imitation of
112-584: The ability of organic remains in the local environment to fossilize. For example, in the Dinosaur Park Formation , fossil hadrosaur eggshell is rare because the breakdown of tannins from local coniferous vegetation would have caused the ancient waters to become acidic. Eggshell fragments are present in only two microfossil sites, both of which are dominated by the preserved shells of invertebrate life, including unionids. The slow dissolution of these shells releasing calcium carbonate into
128-446: The ability to influence water clarity but filtration rates are dependent on water temperature, current velocity, and particle size and concentration. In addition, gill morphology can determine particle size filtered, as well as the rate. Unionidae are distinguished by a unique and complex lifecycle. Most unionids are of separate sex, although some species, such as Elliptio complanata , are known to be hermaphroditic . The sperm
144-531: The family Limnadiidae . Unionidae See text The Unionidae are a family of freshwater mussels , the largest in the order Unionida , the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is at its most diverse in North America, with about 297 recognised taxa, but China and Southeast Asia also support very diverse faunas. Freshwater mussels occupy
160-412: The family Triglyptidae . Ovjurium A clam shrimp (“conchostracan”), member of the family Ovjuridae . Palaeolimnadia A clam shrimp (“conchostracan”), member of the family Limnadiidae . The species Palaeolimnadia baitianbaensis represent the main member of its own fauna section, that comprises other 52 species of Phyllopods Pseudolimnadia A clam shrimp (“conchostracan”), member of
176-441: The family Unionidae inside Unionida . Eolamprotula Isolated Shells A freshwater mussel, member of the family Unionidae inside Unionida . Luochengella Isolated Shells A freshwater mussel, member of the family Unionidae inside Unionida . Modiolus Isolated Shells A freshwater mussel, member of the family Mytilidae inside Mytiloida . Palaeunio Isolated Shells A freshwater mussel, member of
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#1732765802059192-447: The family Unionidae inside Unionida . Palaeomargaritifera Isolated Shells A freshwater mussel, member of the family Margaritiferidae inside Unionida . Pseudocardinia Isolated Shells A freshwater clam, member of the family Pseudocardiniidae inside Trigoniida . Psilunio Isolated Shells A freshwater mussel, member of the family Unionidae inside Unionida . Lioplacodes A freshwater snail, member of
208-457: The family Viviparidae Euestheria A clam shrimp (“conchostracan”), member of the family Lioestheriinae . Iliestheria A clam shrimp (“conchostracan”), member of the family Triglyptidae . Lioestheria A clam shrimp (“conchostracan”), member of the family Lioestheriinae . Loxomegaglypta A clam shrimp (“conchostracan”), member of the family Triglyptidae . Loxomicroglypta A clam shrimp (“conchostracan”), member of
224-404: The fish's gills, where they attach and trigger a tissue response that forms a small cyst in which the young mussel resides. It feeds by breaking down and digesting the tissue of the fish within the cyst. Sex is determined by a region located on the mitochondrial DNA, the male open reading frame (M-ORF) and female open-reading frame (F-ORF). Hermaphroditic mussels lack these regions and contain
240-400: The substrate, with their posterior margins exposed. They pump water through the incurrent aperture , obtaining oxygen and food. They remove phytoplankton and zooplankton, as well as suspended bacteria, fungal spores, and dissolved organic matter. Despite extensive laboratory studies, which of these filtrates unionoids actually process remains uncertain. In high densities, they have
256-403: The water raised the water's pH high enough to prevent the eggshell fragments from dissolving before they could be fossilized. Limnadiidae Limnadiidae is a family of crustaceans in the order Spinicaudata that live in seasonal wetlands, inland saline pools and lakes. They are found on all the world's continents except Antarctica , and are distinguished from other families in
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